Vapor compression cycle having ejector

ABSTRACT

A first evaporator is arranged on a downstream side of an ejector, and a second evaporator is connected to a refrigerant suction inlet of the ejector. A refrigerant evaporation temperature of the second evaporator is lower than that of the first evaporator. The first and second evaporators are used to cool a common subject cooling space and are arranged one after the other in a flow direction of air to be cooled.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part from U.S. patent applicationSer. No. 11/055,795 filed on Feb. 9, 2005 now U.S. Pat. No. 7,178,359and is related to Japanese Patent Application No. 2004-41163 filed onFeb. 18, 2004, Japanese Patent Application No. 2004-74892 filed on Mar.16, 2004, Japanese Patent Application No. 2004-87066 filed on Mar. 24,2004, Japanese Patent Application No. 2004-290120 filed on Oct. 1, 2004and Japanese Patent Application No. 2005-37645 filed on Feb. 15, 2005,the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vapor compression cycle that includesan ejector, which serves as a depressurizing means for depressurizingfluid and which also serves as a momentum transporting pump fortransporting the fluid by entraining action of discharged high velocityworking fluid, so that such a vapor compression cycle is effectivelyapplicable to, for example, a refrigeration cycle of a vehicle airconditioning and refrigerating system, which performs a passengercompartment cooling air conditioning operation and a refrigeratorcooling operation through use of multiple evaporators.

2. Description of Related Art

Japanese Patent No. 1644707 discloses a vapor compression refrigerationcycle of FIG. 25, in which a portion of a refrigerant passage locateddownstream of a radiator 13 branches to two passages 51, 52. A coolingair conditioner evaporator 55 for cooling a vehicle passengercompartment is arranged in the passage 51, and a refrigerator evaporator56 for cooling a refrigerator is arranged in the passage 52.

In the refrigeration cycle of Japanese Patent No. 1644707, the flow ofthe refrigerant is switched between the flow passage 51 for thepassenger compartment cooling air conditioning operation and the flowpassage 52 for the refrigerator cooling operation by switching solenoidvalves 53, 54. In this way, the passenger compartment cooling airconditioning operation, which is performed through use of the coolingair conditioner evaporator 55, and the refrigerator cooling operation,which is performed through use of the refrigerator evaporator 56, arebalanced.

Furthermore, with reference to FIG. 26, Japanese Patent No. 3322263(corresponding to U.S. Pat. Nos. 6,477,857 and 6,574,987) discloses avapor compression refrigeration cycle, in which an ejector 14 is used asa refrigerant depressurizing means and a refrigerant circulating means.In the vapor compression cycle, a first evaporator 61 is arrangedbetween a refrigerant outlet of the ejector 14 and a gas-liquidseparator 63, and a second evaporator 62 is arranged between a liquidrefrigerant outlet of the gas-liquid separator 63 and a suction inlet 14c of the ejector 14.

In the vapor compression cycle of Japanese Patent No. 3322263 shown inFIG. 26, the pressure drop, which is induced by the high velocity flowof the refrigerant at the time of expansion of the refrigerantdischarged from a nozzle portion 14 a of the ejector 14, is used to drawthe gas phase refrigerant, which is discharged from the secondevaporator 62, through the suction inlet 14 c of the ejector 14. Also,the velocity energy of the refrigerant, which is generated at the timeof expansion of the refrigerant in the ejector 14, is converted into thepressure energy at a diffuser portion (a pressurizing portion) 14 b toincrease the pressure of the refrigerant, which is discharged from theejector 14. Thus, the pressurized refrigerant is supplied to thecompressor 12, and thereby the drive force for driving the compressor 12can be reduced. Therefore, the operational efficiency of the cycle canbe improved.

Furthermore, the two evaporators 61, 62 can be used to absorb heat fromand thereby to cool a common space or can be used to absorb heat fromand thereby to cool different spaces, respectively.

However, in the case of the refrigeration cycle of Japanese Patent No.1644707 shown in FIG. 25, the flow passage 51, which is used for thepassenger compartment cooling air conditioning operation, and the flowpassage 52, which is used for refrigerator cooling operation, areswitched through use of a timer. Thus, during the refrigerator coolingoperation, the passenger compartment cooling operation cannot beperformed, so that air conditioning feeling of the passenger may bedeteriorated. Furthermore, due to a difference in the states of theevaporators 55, 56 after the switching operation, the dischargedrefrigerant temperature (i.e., the discharged refrigerant pressure) ofthe compressor 12 will change significantly. For example, in the casewhere the thermal load of the currently operated evaporator 55, 56 afterthe switching operation is relatively large, the compressor 12 could beoperated at the maximum capacity to cause development of the abnormallyhigh pressure in the high pressure side pipe line, which, in turn, couldcause stop of the entire operation.

In the case of the vapor compression cycle of Japanese Patent No.3322263 shown in FIG. 26, the compressor 12 should receive only the gasphase refrigerant, and the second evaporator 62 should receive only theliquid state refrigerant. Thus, the gas-liquid separator 63, whichseparates the refrigerant discharged from the ejector 14 into the gasphase refrigerant and the liquid phase refrigerant, is required.Therefore, the manufacturing costs are disadvantageously increased.

Furthermore, a distributing ratio of the refrigerant to the firstevaporator 61 and to the second evaporator 62 needs to be determinedusing the single ejector 14 while maintaining the refrigerantcirculating (gas phase refrigerant drawing) operation of the ejector 14.Thus, it is difficult to appropriately adjust the flow rates of therefrigerant of the first and second evaporators 61, 62.

Furthermore, the two evaporators 61, 62 can be used to absorb heat fromand thereby to cool a common space or can be alternatively used toabsorb heat from and thereby to cool different spaces, respectively.Also, it is recited that these two evaporators 61, 62 may be used tocool a room.

However, Japanese Patent No. 3322263 does not recite a specificarrangement of the two evaporators 61, 62 for cooling the room by thetwo evaporators 61, 62.

Furthermore, another previously proposed refrigeration cycle, whichincludes a plurality of evaporators, is shown in FIG. 27. FIG. 27 is aschematic diagram of the refrigeration cycle, which includes apreviously proposed thermostatic expansion valve 105. In therefrigeration cycle, a refrigerant circulation passage R is divided intotwo passages R1, R2 at a point located on the downstream side of aradiator 102. One evaporator 104 is provided in the passage R1 and isused to perform, for example, passenger compartment cooling airconditioning operation. The other evaporator 106 is provided in thepassage R2 and is used to perform, for example, refrigerator coolingoperation.

In the case of the refrigeration cycle, which uses the multipleevaporators, such as of a vehicle air conditioning system including acool box (the refrigerator), the evaporator 104 for the passengercompartment cooling air conditioning operation and the evaporator 106for the refrigerator cooling operation are temperature controlled to thedesired evaporation temperatures, respectively, by intermittentlyopening and closing a solenoid valve 107 arranged in the refrigerantpassage R2 for the refrigerator cooling operation to supply therefrigerant to the refrigerant passage R1 for the passenger compartmentcooling air conditioning operation. Furthermore, the thermostaticexpansion valve 105 and a fixed metering device 108 are provided as adepressurizing means. In FIG. 27, numeral 101 indicates a refrigerantcompressor, and numeral 109 indicates a check valve. FIG. 28 is aschematic diagram, in which a box type thermostatic expansion valve 105is provided in the refrigeration cycle of FIG. 27.

In a case where an ejector is used in the refrigeration cycle of FIG.28, adjustment (e.g., the flow rate adjustment) to correspond with theload changes and effective response to the rapid change in therotational speed of the compressor are required. To achieve them,Japanese Unexamined Patent Publication No. 2004-44906 (U.S. patentapplication Publication No. 2004/0007014A1) discloses an ejector, whichshows a high efficiency and a high responsibility throughout the entireload range.

However, for example, when the ejector of Japanese Unexamined PatentPublication No. 2004-44906 (U.S. patent application Publication No.2004/0007014A1) is used in the refrigeration cycle of FIG. 28, whichincludes the box type thermostatic expansion valve 105, the orientationof the ejector is limited. Thus, there is less freedom in designing ofthe refrigeration cycle, i.e., the vapor compression cycle having theejector.

SUMMARY OF THE INVENTION

The present invention addresses the above disadvantages. Thus, it is anobjective of the present invention to provide a vapor compression cycle,which includes multiple evaporators and solves or alleviates at leastone of the above disadvantages.

To achieve the objective of the present invention, there is provided avapor compression cycle, which includes a compressor, a radiator, anejector, a first evaporator, a first branched passage, a first meteringmeans and a second evaporator. The compressor draws and compressesrefrigerant. The radiator radiates heat from the compressed highpressure refrigerant discharged from the compressor. The ejectorincludes a nozzle portion, a gas phase refrigerant suction inlet and apressurizing portion. The nozzle portion depressurizes and expands therefrigerant on a downstream side of the radiator. Gas phase refrigerantis drawn from the gas phase refrigerant suction inlet by action of aflow of the high velocity refrigerant discharged from the nozzleportion. The pressurizing portion converts a velocity energy of a flowof a mixture of the high velocity refrigerant and the gas phaserefrigerant into a pressure energy. The first evaporator evaporates therefrigerant, which is outputted from the ejector, to achieve arefrigeration capacity. A refrigerant outlet of the first evaporator isconnected to a suction inlet of the compressor. The first branchedpassage branches a flow of the refrigerant at a corresponding branchingpoint located between the radiator and the ejector. The first branchedpassage conducts the branched flow of the refrigerant to the gas phaserefrigerant suction inlet of the ejector. The first metering meansdepressurizes the refrigerant on a downstream side of the radiator. Thesecond evaporator is arranged in the first branched passage. The secondevaporator evaporates the refrigerant to achieve a refrigerationcapacity.

To achieve the objective of the present invention, there is alsoprovided a vapor compression cycle, which includes a compressor, aradiator, a first metering means, a first evaporator, an ejector, afirst branched passage, a second metering means and a second evaporator.The compressor draws and compresses refrigerant. The radiator radiatesheat from the compressed high pressure refrigerant discharged from thecompressor. The first metering means depressurizes the refrigerant on adownstream side of the radiator. The first evaporator is connectedbetween a refrigerant outlet of the first metering means and a suctioninlet of the compressor. The first evaporator evaporates the lowpressure refrigerant, which is outputted at least from the firstmetering means, to achieve a refrigeration capacity. The ejectorincludes a nozzle portion, a gas phase refrigerant suction inlet and apressurizing portion. The nozzle portion depressurizes and expands therefrigerant on a downstream side of the radiator. Gas phase refrigerantis drawn from the gas phase refrigerant suction inlet by action of aflow of the high velocity refrigerant discharged from the nozzleportion. The pressurizing portion converts a velocity energy of a flowof a mixture of the high velocity refrigerant and the gas phaserefrigerant into a pressure energy. The first branched passage branchesa flow of the refrigerant at a corresponding branching point locatedbetween the radiator and the first metering means. The first branchedpassage conducts the branched flow of the refrigerant to the gas phaserefrigerant suction inlet of the ejector. The second metering means isarranged in the first branched passage and depressurizes the refrigeranton a downstream side of the radiator. The second evaporator is arrangedin the first branched passage on a downstream side of the secondmetering means. The second evaporator evaporates the refrigerant toachieve a refrigeration capacity.

To achieve the objective of the present invention, there is alsoprovided a vapor compression cycle, which includes a compressor, aradiator, an ejector, a first evaporator and a second evaporator. Thecompressor draws and compresses refrigerant. The radiator radiates heatfrom the compressed high pressure refrigerant discharged from thecompressor. The ejector includes a nozzle portion, a refrigerant suctioninlet, a mixing portion and a pressurizing portion. The nozzle portiondepressurizes and expands the refrigerant on a downstream side of theradiator. Refrigerant is drawn from the refrigerant suction inlet byaction of a flow of the high velocity refrigerant discharged from thenozzle portion. The high velocity refrigerant discharged from the nozzleportion and the drawn refrigerant supplied from the suction inlet aremixed in the mixing portion. The pressurizing portion converts avelocity energy of a flow of mixed refrigerant, which is mixed throughthe mixing portion, into a pressure energy. The first evaporator isconnected to a downstream side of the ejector. The second evaporator isconnected to the suction inlet of the ejector. The first evaporator andthe second evaporator are constructed integrally to cool an air flowthat is directed to a common subject cooling space.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objectives, features andadvantages thereof, will be best understood from the followingdescription, the appended claims and the accompanying drawings in which:

FIG. 1 is a schematic view of a vapor compression cycle according to afirst embodiment of the present invention;

FIG. 2 is a schematic view of a vapor compression cycle according to asecond embodiment;

FIG. 3 is a flow chart showing control operation performed by an ECU inthe second embodiment;

FIG. 4 is a diagram showing various operating modes and controloperation of corresponding components by the ECU according to the secondembodiment;

FIG. 5 is a schematic view of a vapor compression cycle according to athird embodiment;

FIG. 6 is a diagram showing various operating modes and controloperation of corresponding components by the ECU according to the thirdembodiment;

FIG. 7 is a schematic view of a vapor compression cycle according to afourth embodiment;

FIG. 8 is a schematic view of a vapor compression cycle according to afifth embodiment;

FIG. 9 is a schematic view of a vapor compression cycle according to asixth embodiment;

FIG. 10 is a schematic view of a vapor compression cycle according to aseventh embodiment;

FIG. 11 is a schematic view of a vapor compression cycle according to aneighth embodiment;

FIG. 12 is a schematic view of a vapor compression cycle according to aninth embodiment;

FIG. 13 is a schematic view of a vapor compression cycle according to atenth embodiment;

FIG. 14 is a schematic view of a vapor compression cycle, which includesa refrigeration cycle device, according to a eleventh embodiment of theinvention;

FIG. 15 is a cross sectional view of a box type thermostatic expansionvalve according to the eleventh embodiment;

FIG. 16 is a cross sectional view of an ejector according to theeleventh embodiment;

FIG. 17A is a descriptive diagram for describing advantages of theejector of FIG. 16;

FIG. 17B is a descriptive diagram showing various states of refrigerantin the ejector of FIG. 16;

FIG. 18A is a partial cross sectional view of a refrigeration cycledevice according to a twelfth embodiment of the present invention;

FIG. 18B is a view seen in a direction of XVIIIB in FIG. 18A;

FIG. 19 is a schematic view showing a structure of a vehicular vaporcompression cycle according to a thirteenth embodiment of the presentinvention;

FIG. 20 is a schematic perspective view showing an integrated structureof first and second evaporators according to the thirteenth embodiment;

FIG. 21 is a schematic perspective view showing an integrated structureof first and second evaporators according to a fourteenth embodiment;

FIG. 22 is a schematic view showing a structure of a vehicular vaporcompression cycle according to a fifteenth embodiment;

FIG. 23 is a schematic view showing a structure of a vehicular vaporcompression cycle according to a sixteenth embodiment;

FIG. 24 is a schematic view showing a modification of the integratedstructure of the first and second evaporators of the invention;

FIG. 25 is a schematic view of a prior art refrigeration cycle;

FIG. 26 is a schematic view of a prior art vapor compression cycle;

FIG. 27 is a schematic diagram of a refrigeration cycle, which uses apreviously proposed thermostatic expansion valve; and

FIG. 28 is a schematic diagram showing a case where a box typethermostatic expansion valve is used in the refrigeration cycle of FIG.27.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments of the present invention will be described withreference to the accompanying drawings.

FIRST EMBODIMENT

FIG. 1 shows an exemplary case where a vapor compression cycle accordingto a first embodiment of the present invention is implemented in avehicle air conditioning and refrigerating system. The vapor compressioncycle includes a refrigerant circulation passage 11, through withrefrigerant is circulated. A compressor 12 is arranged in therefrigerant circulation passage 11. The compressor 12 draws andcompresses the refrigerant supplied thereto.

In the present embodiment, the compressor 12 is rotated by, for example,a vehicle drive engine (not shown) through a belt or the like. Thecompressor 12 is a variable displacement compressor, which can adjust arefrigerant discharge rate through a change in its displacement. Thedisplacement is defined as an amount of refrigerant discharged from thecompressor 12 per rotation of the compressor 12. The displacement of thecompressor 12 can be changed by changing an intake volume of therefrigerant in the compressor 12.

A swash plate compressor is most commonly used for this purpose and canbe used as the variable displacement compressor 12. Specifically, in theswash plate compressor, a tilt angle of a swash plate is changed tochange a piston stroke and thereby to change the intake volume of therefrigerant. A pressure (control pressure) in a swash plate chamber ofthe compressor 12 is changed by a pressure control electromagneticdevice 12 a, which constitutes a displacement control mechanism, so thata tilt angle of the swash plate is externally and electricallycontrolled.

A radiator 13 is arranged downstream of the compressor 12 in arefrigerant flow direction. The radiator 13 exchanges heat between thehigh pressure refrigerant, which is discharged from the compressor 12,and the external air (external air supplied from outside of thevehicle), which is blown toward the radiator 13 by a cooling fan (notshown), so that the high pressure refrigerant is cooled.

An ejector 14 is arranged further downstream of the radiator 13 in therefrigerant flow direction. The ejector 14 serves as a depressurizingmeans for depressurizing the fluid and is formed as amomentum-transporting pump, which performs fluid transportation byentraining action of discharged high velocity working fluid (see JIS Z8126 Number 2.1.2.3).

The ejector 14 includes a nozzle portion 14 a and a suction inlet 14 c.The nozzle portion 14 a reduces a cross sectional area of therefrigerant passage, which conducts the refrigerant discharged from theradiator 13, to isentropically depressurize and expand the high pressurerefrigerant. The suction inlet 14 c is arranged in a space, in which arefrigerant discharge outlet of the nozzle portion 14 a is located. Thesuction inlet 14 c draws gas phase refrigerant supplied from a secondevaporator 18. Furthermore, a diffuser portion 14 b, which serves as apressurizing portion, is arranged downstream of the nozzle portion 14 aand the suction inlet 14 c in the refrigerant flow direction. Thediffuser portion 14 b is formed to progressively increase a crosssectional area of its refrigerant passage toward its downstream end, sothat the diffuser portion 14 b decelerates the refrigerant flow andincreases the refrigerant pressure, i.e., the diffuser portion 14 bconverts the velocity energy of the refrigerant to the pressure energy.

The refrigerant discharged from the diffuser portion 14 b of the ejector14 is supplied to a first evaporator 15. The first evaporator 15 isarranged in, for example, an air passage of a vehicle passengercompartment air conditioning unit (not shown) to cool the air dischargedinto the passenger compartment and thereby to cool the passengercompartment.

More specifically, the passenger compartment conditioning air is blownfrom an electric blower (a first blower) 26 of the vehicle passengercompartment air conditioning unit toward the first evaporator 15. In thefirst evaporator 15, the low pressure refrigerant, which has beendepressurized by the ejector 14, absorbs heat from the passengercompartment conditioning air and thereby evaporates into gas phaserefrigerant, so that the passenger compartment conditioning air iscooled to cool the passenger compartment. The gas phase refrigerant,which has been evaporated in the first evaporator 15, is drawn into thecompressor 12 and is re-circulated through the refrigerant circulationpassage 11.

Furthermore, in the vapor compression cycle of the present embodiment, afirst branched passage 16 is formed. The first branched passage 16 isbranched from a corresponding branching portion of the refrigerantcirculation passage 11 between the radiator 13 and the ejector 14 on thedownstream side of the radiator 13 and is then rejoined with therefrigerant circulation passage 11 at the suction inlet 14 c of theejector 14.

A first flow rate control valve (a first metering mechanism or a firstmetering means) 17 is arranged in the first branched passage 16. Thefirst flow rate control valve 17 controls the flow rate of therefrigerant and depressurizes the refrigerant. A valve opening degree ofthe first flow rate control valve 17 can be electrically controlled. Thesecond evaporator 18 is arranged downstream of the first flow ratecontrol valve 17 in the refrigerant flow direction.

The second evaporator 18 is arranged in, for example, a vehiclerefrigerator (not shown) to cool an interior of the refrigerator.Internal air of the refrigerator is blown by an electric blower (asecond blower) 27 toward the second evaporator 18.

In the present embodiment, the pressure control electromagnetic device12 a of the variable displacement compressor 12, the first and secondblowers 26, 27 and the first flow rate control valve 17 are electricallycontrolled by a corresponding control signal outputted from anelectronic control unit (ECU).

Next, operation of the present embodiment will be described withreference to the above structure. When the compressor 12 is driven bythe vehicle engine, the refrigerant is compressed in the compressor 12,and therefore the high temperature and high pressure refrigerant isdischarged from the compressor 12 in a direction of an arrow A and issupplied to the radiator 13. In the radiator 13, the high temperaturerefrigerant is cooled by the external air and is thus condensed. Theliquid state refrigerant, which is discharged from the radiator 13 isdivided into a flow of an arrow B passing through the refrigerantcirculation passage 11 and a flow of an arrow C passing through thefirst branched passage 16.

The refrigerant (the arrow C), which passes through the first branchedpassage 16, is depressurized through the first flow rate control valve17 and thus becomes the low pressure refrigerant. Then, in the secondevaporator 18, the low pressure refrigerant absorbs heat from theinterior air of the refrigerator, which is blown by the second blower27, so that the refrigerant evaporates. In this way, the secondevaporator 18 cools the interior of the refrigerator.

Here, the refrigerant flow rate in the first branched passage 16, i.e.,the refrigerant flow rate in the second evaporator 18 is adjusted bycontrolling the valve opening degree of the first flow rate controlvalve 17 of the first branched passage 16 through the ECU (a controlmeans) 25. Therefore, the cooling capacity of the subject cooling space(specifically, the interior space of the refrigerator), which is cooledby the second evaporator 18, is controlled by controlling the valveopening degree of the first flow rate control valve 17 and a rotationalspeed, i.e., an rpm (the air flow rate) of the second blower 27 throughthe ECU 25.

The gas phase refrigerant, which is outputted from the second evaporator18, is drawn into the suction inlet 14 c of the ejector 14. Therefrigerant flow of the arrow B, which flows in the refrigerantcirculation passage 11, is supplied to a refrigerant inlet (a drive flowinlet) of the nozzle portion 14 a of the ejector 14. The refrigerant isdepressurized and is expanded through the nozzle portion 14 a. Thus, thepressure energy of the refrigerant is converted into the velocity energyin the nozzle portion 14 a and is discharged from the outlet of thenozzle portion 14 at the high speed. Due to the decrease in therefrigerant pressure, the gas phase refrigerant, which is evaporated inthe second evaporator 18, is drawn through the suction inlet 14 c.

The refrigerant, which is discharged from the nozzle portion 14 a, andthe refrigerant, which is drawn into the suction inlet 14 c, are mixedat the downstream side of the nozzle portion 14 a and are then suppliedto the diffuser portion 14 b. Due to the increase in the cross sectionalarea of the refrigerant passage in the diffuser portion 14 b, thevelocity energy (expansion energy) of the refrigerant is converted tothe pressure energy. Thus, the pressure of the refrigerant is increased.The refrigerant discharged from the diffuser portion 14 b of the ejector14 is supplied to the first evaporator 15.

In the first evaporator 15, the refrigerant absorbs heat from theconditioning air to be discharged into the vehicle passengercompartment, so that the refrigerant evaporates. After the evaporation,the gas phase refrigerant is drawn into the compressor 12 and iscompressed. Thereafter, the refrigerant is discharged from thecompressor 12 and flows in the direction of the arrow A in therefrigerant circulation passage 11. Here, the ECU 25 controls the volume(displacement) of the compressor 12 to control the refrigerant dischargerate of the compressor 12, so that the flow rate of the refrigerantsupplied to the first evaporator 15 is adjusted. Furthermore, the ECU 25controls the rpm (the air flow rate) of the first blower 26 to controlthe cooling capacity for cooling the subject cooling space, which iscooled by the first evaporator 15, more specifically the coolingcapacity for cooling the vehicle passenger compartment.

Next, advantages of the first embodiment will be described.

(1) The first evaporator 15 is arranged downstream of the diffuserportion 14 b of the ejector 14, and the first branched passage 16branches from the refrigerant circulation passage 11 at the downstreamside of the radiator 13 and is connected to the suction inlet 14 c ofthe ejector 14. The first flow rate control valve 17 and the secondevaporator 18 are arranged in the first branched passage 16. Therefore,the cooling operation can be simultaneously performed at both the firstand second evaporators 15, 18.

(2) The refrigerant evaporation pressure of the first evaporator 15 isthe pressure after the pressurization through the diffuser portion 14 b.In contrast, the outlet of the second evaporator 18 is connected to thesuction inlet 14 c of the ejector 14. Thus, the lowest pressure rightafter the depressurization at the nozzle portion 14 a can be applied tothe outlet of the second evaporator 18.

In this way, the refrigerant evaporation pressure (the refrigerantevaporation temperature) of the second evaporator 18 can be made lowerthan that of the first evaporator 15. Thus, the cooling operation at thehigher temperature range, which is suitable for cooling the vehiclepassenger compartment, can be performed by the first evaporator 15. Atthe same time, the cooling operation at the lower temperature range,which is lower than the higher temperature range and is suitable forcooling the interior of the refrigerator, can be performed by the secondevaporator 18.

As described above, even with the above simple structure, in which thefirst branched passage 16 is added, the cooling operation at the highertemperature range, which is suitable for cooling the vehicle passengercompartment, and the cooling operation at the lower temperature range,which is suitable for cooling the interior of the refrigerator, can beimplemented. That is, the cooling operations at the two differenttemperature ranges can be implemented.

(3) As discussed above, the flow rate of the refrigerant supplied to thefirst evaporator 15 can be controlled by controlling the refrigerantdischarge rate of the compressor 12. Furthermore, the cooling capacityof the first evaporator 15 can be controlled by controlling the air flowrate of the first blower 26.

Furthermore, the cooling capacity of the second evaporator 18 can becontrolled by controlling the refrigerant flow rate through the firstflow rate control valve 17 and by controlling the air flow rate of thesecond blower 27.

As discussed above, the cooling capacity of the first evaporator 15 andthe cooling capacity of the second evaporator 18 can be individuallycontrolled. Thus, it is relatively easy to correspond to a change in thethermal load in the first and second evaporators 15, 18.

(4) The depressurized two-phase refrigerant, which is depressurizedthrough the first flow rate control valve 17 and includes both the gasphase refrigerant and the liquid phase refrigerant, can be supplied tothe second evaporator 18 through the first branched passage 16. Thus,unlike Japanese Patent No. 3322263 of FIG. 26, there is no need toprovide the gas-liquid separator 63 at the downstream side of the firstevaporator 61 to supply the liquid phase refrigerant to the secondevaporator 62.

Furthermore, as discussed above, the control of the refrigerant flowrate at the first evaporator 15 and the control of the refrigerant flowrate at the second evaporator 18 can be individually performed throughthe control of the refrigerant discharge rate of the compressor 12 andalso through the control of the valve opening degree of the first flowrate control valve 17. Thus, the control of the refrigerant flow rate ofeach evaporator 15, 18 can be appropriately performed based on itsthermal load. Therefore, the refrigerant flow rate can be adjusted insuch a manner that the entire refrigerant becomes the gas phaserefrigerant at the first evaporator 15, which is located downstream ofthe ejector 14.

Therefore, according to the present embodiment, it is possible toeliminate the gas-liquid separator 63, which is required in JapanesePatent No. 3322263 of FIG. 26. As a result, the manufacturing costs ofthe vapor compression cycle can be reduced.

(5) The pressure of the refrigerant is increased by the diffuser portion14 b of the ejector 14, so that the intake refrigerant pressure of thecompressor 12 can be increased. In this way, the drive power for drivingthe compressor 12 can be minimized to improve the efficiency of thecycle.

SECOND EMBODIMENT

FIG. 2 shows a vapor compression cycle of a second embodiment, which issimilar to that of the first embodiment except first and second solenoidvalves (a first opening and closing means and a second opening andclosing means) 19, 20. The first solenoid valve 19 opens and closes therefrigerant circulation passage 11 on the upstream side of the ejector14. The second solenoid valve 20 opens and closes the first branchedpassage 16 on the upstream side of the first flow rate control valve 17.Similar to the pressure control electromagnetic device 12 a of thecompressor 12, the opening and closing of the first and second solenoidvalves 19, 20 are controlled by a corresponding signal supplied from theECU 25.

Selection of an operating mode conducted by the ECU 25 will be describedwith reference to FIG. 3. First, user input information, temperatureinformation of each subject cooling space and the temperatureinformation of each evaporator 15, 18 are inputted to the ECU 25 at stepS110. The user information includes, for example, presence of a need(ON, OFF) for cooling the subject cooling space and the desired settemperature of the subject cooling space.

Next, at step S120, a target temperature of each subject cooling spaceor a target temperature of each evaporator 15, 18 is determined by theECU 25 based on the information inputted at step S110. In this way, thesubject evaporator(s), which needs to be operated to achieve therequired cooling capacity by supplying the refrigerant therethrough, isdetermined. Based on the respective target temperature, the bestoperating mode is determined with reference to, for example, FIG. 4 atstep S130.

In the present embodiment, a first evaporator operating mode (FIRSTEVAPO. in FIG. 4), a second evaporator operating mode (SECOND EVAPO. inFIG. 4) and a multiple evaporator operating mode (MULTIPLE EVAPO. inFIG. 4) are provided. In the first evaporator operating mode, only thefirst evaporator 15 is operated to attain its cooling capacity. In thesecond evaporator operating mode, only the second evaporator 18 isoperated to attain its cooling capacity. In the multiple evaporatoroperating mode, both the first and second evaporators 15, 18 areoperated to attain its cooling capacity.

For example, when a user actuates the cycle and sets the temperature ofthe subject cooling space, which is cooled by the first evaporator 15,i.e., when the first evaporator 15 needs to be operated to attain itscooling capacity, the first evaporator operating mode is selected. Basedon the selected operating mode, the ECU 25 controls the first and secondsolenoid valves 19, 20, the first flow rate control valve (FIRST CONTROLVALVE in FIG. 4) 17 and the first and second blowers 26, 27 in themanner indicated in FIG. 4.

Thereafter, the ECU 25 controls the electrical device(s), such as thepressure control electromagnetic device 12 a of the compressor 12, toadjust the temperature of the subject cooling space to the settemperature at step S140. In the above described manner, each operatingmode shown in FIG. 4 can be selected and can be set by the ECU 25.

This point will be more specifically described. At the time of the firstevaporator operating mode, the ECU 25 opens the first solenoid valve 19and closes the second solenoid valve 20. Then, the ECU 25 controls thevolume (the refrigerant discharge rate) of the compressor 12 to controlthe flow rate of the refrigerant supplied to the first evaporator 15. Inthis way, it is possible to adjust the total amount of heat, which isabsorbed by the refrigerant at the first evaporator 15 from the air tobe discharged into the subject cooling space. Furthermore, the flow rateof the cooling air into the subject cooling space, which is cooled bythe first evaporator 15, is controlled by controlling the rpm (the airflow rate) of the first blower 26. In this way, the cooling capacity ofthe first evaporator 15 (more specifically, the cooling capacity forcooling the vehicle passenger compartment) is adjusted.

Furthermore, in the second evaporator operating mode, the ECU 25 closesthe first solenoid valve 19 and opens the second solenoid valve 20. Theflow rate of the refrigerant, which is supplied to the second evaporator18, is controlled by controlling the volume (the refrigerant dischargerate) of the compressor 12 and the valve opening degree of the firstflow rate control valve 17.

Furthermore, the flow rate of the cooling air into the subject coolingspace, which is cooled by the second evaporator 18, is controlled bycontrolling the rpm (the air flow rate) of the second blower 27. In thisway, the cooling capacity of the second evaporator 18 (morespecifically, the cooling capacity for cooling the interior of therefrigerator) is controlled.

Furthermore, in the multiple evaporator operating mode, the ECU 25 opensboth the first and second solenoid valves 19, 20. Then, the ECU 25controls the volume (the refrigerant discharge rate) of the compressor12 to control the flow rate of the refrigerant supplied to the firstevaporator 15. The flow rate of the refrigerant, which is supplied tothe second evaporator 18, is adjusted by adjusting the valve openingdegree of the first flow rate control valve 17.

In addition, by individually controlling the rpm (the air flow rate) ofthe first blower 26 and the rpm (the air flow rate) of the second blower27, the flow rate of the cooling air discharged into the subject coolingspace of the first evaporator 15 and the flow rate of the cooling airdischarged into the subject cooling space of the second evaporator 18are individually controlled. In this way, the cooling capacity of thefirst evaporator 15 and the cooling capacity of the second evaporator 18are individually controlled.

When the pressure of the refrigerant, which is supplied to the ejector14, is increased by increasing the volume (the refrigerant dischargerate) of the compressor 12, the suction capacity of the ejector 14 fordrawing the gas phase refrigerant, which is evaporated in the secondevaporator 18, is increased. Even in this way, the flow rate of therefrigerant, which flows through the second evaporator 18, can becontrolled.

Furthermore, in the second evaporator operating mode, the refrigerant issupplied only to the second evaporator 18, so that the refrigerationoil, which remains in the second evaporator 18, can be returned to thecompressor 12.

THIRD EMBODIMENT

FIG. 5 shows a vapor compression cycle according to a third embodiment.The vapor compression cycle of the third embodiment is similar to thatof the second embodiment except a second branched passage 23. The secondbranched passage 23 connects between a portion (a branching point) ofthe first branched passage 16, which is on the upstream side of thefirst flow rate control valve 17, and a portion (a merging point) of therefrigerant passage 11, which connects between the first evaporator 15and the compressor 12.

A second flow rate control valve (a second metering means) 24 and athird solenoid valve (a third opening and closing means) 28 are arrangedin the second branched passage 23. The second flow rate control valve 24controls the flow rate of the refrigerant and depressurizes therefrigerant. The third solenoid valve 28 opens and closes the secondbranched passage 23. Furthermore, a third evaporator 22 is arranged onthe downstream side of the second flow rate control valve 24 in therefrigerant flow direction in the second branched passage 23. The air ofa subject cooling space of the third evaporator 22 is blown by anelectric blower (a third blower) 29 toward the third evaporator 22.

Here, a downstream side of the third evaporator 22 is connected to adownstream side of the first evaporator 15 and is thus connected to thesuction inlet side of the compressor 12. Thus, the refrigerantevaporation pressure of the first evaporator 15 and the refrigerantevaporation pressure of the third evaporator 22 are generally the sameas the suction pressure of the compressor 12. Thus, the refrigerantevaporation temperature of the first evaporator 15 and the refrigerantevaporation temperature of the third evaporator 22 are also the same.

Therefore, for example, a front seat side space of the vehicle passengercompartment can be set as the subject cooling space of the firstevaporator 15, and a rear seat side space of the vehicle passengercompartment can be set as the subject cooling space of the thirdevaporator 22. In this way, the front seat side space and the rear seatside space of the vehicle passenger compartment can be simultaneouslycooled by the first and third evaporators 15, 22, respectively.

In the third embodiment, the second flow rate control valve 24, thethird solenoid valve 28 and the third blower 29 are also controlled by acorresponding control signal, which is supplied from the ECU 25.

The control operation of the ECU 25 of the third embodiment issubstantially the same as that of the second embodiment except step S130of FIG. 3. That is, in the second embodiment, the operating mode isdetermined with reference to FIG. 4. In contrast, in the thirdembodiment, the operating mode is determined with reference to FIG. 6.

In the third embodiment, the number of controlled elements, which arecontrolled by the ECU 25, is increased in comparison to that of thesecond embodiment, so that the number of the operating modes isincreased, as shown in FIG. 6. However, similar to the secondembodiment, the control flow of the ECU 25 is determined based on theoperating mode of the corresponding required evaporator(s), which isrequired to attain the required cooling capacity (see S130 in FIG. 3).

The operating modes of the third embodiment will be described further.The first evaporator operating mode (FIRST EVAPO.) and the secondevaporator operating mode (SECOND EVAPO.) of the third embodiment aresimilar to those of the second embodiment. In the third evaporatoroperating mode (THIRD EVAPO.), the ECU 25 closes the first and secondsolenoid valves 19, 20 and opens the third solenoid valve 28.

The flow rate of the refrigerant, which is supplied to the thirdevaporator 22, is controlled by controlling the volume (the refrigerantdischarge rate) of the compressor 12 and the valve opening degree of thesecond flow rate control valve (SECOND CONTROL VALVE) 24. Furthermore,the flow rate of the cooling air into the subject cooling space of thethird evaporator 22 is controlled by controlling the rpm (the air flowrate) of the third blower 29. In this way, the cooling capacity of thethird evaporator 22 (more specifically, the cooling capacity for coolingthe rear seat side space of the vehicle passenger compartment) iscontrolled.

In a first and second evaporator operating mode (FIRST, SECOND EVAPO. inFIG. 6), the ECU 25 opens the first and second solenoid valves 19, 20and closes the third solenoid valve 28. The compressor 12, the firstflow rate control valve 17 and the first and second blowers 26, 27 arecontrolled in a manner similar to that of the multiple evaporatoroperating mode of the second embodiment to control the coolingcapacities of the first and second evaporators 15, 18.

In a first and third evaporator operating mode (FIRST, THIRD EVAPO. inFIG. 6), the ECU 25 opens the first and third solenoid valves 19, 28 andcloses the second solenoid valve 20. Then, the flow rate of therefrigerant, which is supplied to the first evaporator 15, is controlledby controlling the volume (the refrigerant discharge rate) of thecompressor 12. Also, the flow rate of the refrigerant, which is suppliedto the third evaporator 22, is controlled by controlling the valveopening degree of the second flow rate control valve 24. Furthermore,the flow rate of the cooling air into the subject cooling space of thefirst evaporator 15 and the flow rate of the cooling air into thesubject cooling space of the third evaporator 22 are controlled bycontrolling the rpm (the air flow rate) of the first blower 26 and therpm (the air flow rate) of the third blower 29, respectively. In thisway, the cooling capacity of the first evaporator 15 and the coolingcapacity of the third evaporator 22 are controlled.

In a second and third evaporator operating mode (SECOND, THIRD EVAPO.),the ECU 25 opens the second and third solenoid valves 20, 28 and closesthe first solenoid valve 19. The cooling capacity of the secondevaporator 18 and the cooling capacity of the third evaporator 22 arecontrolled by controlling the volume (the refrigerant discharge rate) ofthe compressor 12, the valve opening degrees of the first and secondflow rate control valves 17, 24 and the air flow rates of the second andthird blowers 27, 29.

In a first to third evaporator operating mode (ALL EVAPO. in FIG. 6),the ECU 25 opens all of the first to third solenoid valves 19, 20, 28.Then, the flow rate of the refrigerant, which is supplied to the firstevaporator 15, is controlled by controlling the volume (the refrigerantdischarge rate) of the compressor 12. Also, the flow rate of therefrigerant to the second evaporator 18 and the flow rate of therefrigerant to the third evaporator 22 are controlled by controlling thevalve opening degrees of the first and second flow rate control valve17, 24, respectively.

Furthermore, the rpm's (the air flow rates) of the first to thirdblowers 26, 27, 29 are controlled to control the flow rates of thecooling air discharged into the corresponding subject cooling spaces,respectively. In this way, the cooling capacity of the first evaporator15, the cooling capacity of the second evaporator 18 and the coolingcapacity of the third evaporator 22 are individually controlled.

In the above described manner, each operating mode shown in FIG. 6 canbe selected and can be set by the ECU 25. Thus, the common subjectcooling space or the multiple subject cooling spaces can be controlledby one or more of the three evaporators 15, 18, 22.

Furthermore, in the second evaporator operating mode, the refrigerant issupplied only to the second evaporator 18. Also, in the third evaporatoroperating mode, the refrigerant is supplied only to the third evaporator22. Thus, the refrigerant remained in the second evaporator 18 or thethird evaporator 22 can be returned to the compressor 12.

FOURTH EMBODIMENT

FIG. 7 shows a vapor compression cycle of a fourth embodiment. The vaporcompression cycle of the fourth embodiment is similar to the vaporcompression cycle of the first embodiment except a third branchedpassage 21. The third branched passage 21 extends from a portion (abranching point) of the refrigerant circulation passage 11, which islocated between the ejector 14 and the first evaporator 15, to anotherportion (a merging point) of the refrigerant circulation passage 11,which is located between the first evaporator 15 and the compressor 12.A fourth evaporator (or a third evaporator) 30 is arranged in the thirdbranched passage 21. A fourth blower (or a third blower) 31, which is anelectric blower, is arranged to oppose the fourth evaporator 30.

In this way, in addition to the first and second evaporators 15, 18, apredetermined subject cooling space can be cooled by the fourthevaporator 30. Here, a downstream side of the fourth evaporator 30 isconnected to a downstream side of the first evaporator 15 and is thusconnected to the suction inlet side of the compressor 12. Thus, therefrigerant evaporation pressure of the first evaporator 15 and therefrigerant evaporation pressure of the fourth evaporator 30 aregenerally the same as the suction pressure of the compressor 12. Thus,the refrigerant evaporation temperature of the first evaporator 15 andthe refrigerant evaporation temperature of the fourth evaporator 30 arealso the same.

Even in the fourth embodiment, similar to the third embodiment, thecommon subject cooling space or the multiple subject cooling spaces canbe cooled by the three evaporators 15, 18, 30.

FIFTH EMBODIMENT

In each of the first to fourth embodiments, the ejector 14 and the firstevaporator 15 are connected in series. Thus, the ejector 14 has the flowrate adjusting function for adjusting the flow rate of the refrigerantto the first evaporator 15 and also has the pumping function forcreating a refrigerant pressure difference between the first evaporator15 and the second evaporator 18.

Therefore, at the time of designing the ejector 14, the requiredspecification for achieving both the flow rate adjusting function andthe pumping function should be satisfied. Thus, in order to achieve theflow rate adjusting function for adjusting the flow rate of therefrigerant to the first evaporator 15, the design needs to rely on thefirst evaporator 15. As a result, the operation of the vapor compressioncycle at the high efficiency becomes difficult.

Thus, in the fifth embodiment, the ejector 14 has only the pumpingfunction without the flow rate adjusting function for adjusting the flowrate of the first evaporator 15 to allow easy designing of the ejector14, which enables the highly efficient operation of the vaporcompression cycle.

The fifth embodiment will be described more specifically with referenceto FIG. 8. In the refrigerant circulation passage 11, a dedicatedmetering mechanism (a first metering means) 32 is provided between theoutlet of the radiator 13 and the inlet of the first evaporator 15.Furthermore, in the fifth embodiment, the ejector 14 is not provided inthe refrigerant circulation passage 11. Rather, the ejector 14 isprovided in parallel with the metering mechanism 32.

Although various devices can be used as the metering mechanism 32, athermostatic expansion valve, which controls its valve opening degree ina manner that keeps the superheat of the refrigerant at the outlet ofthe first evaporator 15 at a predetermined value, is used as themetering mechanism 32 in the present embodiment.

A metering mechanism (a second metering means) 17 and the secondevaporator 18 are arranged in series in the first branched passage 16,which branches from the portion of the refrigerant circulation passage11 between the outlet of the radiator 13 and the inlet of the ejector14. Furthermore, the outlet of the second evaporator 18 is connected tothe suction inlet 14 c of the ejector 14. Although various devices canbe used as the metering mechanism 17 of the first branched passage 16, afixed metering device, such as a capillary tube of a simple structure,is used as the metering mechanism 17 in this embodiment.

Next, operation of the fifth embodiment will be described. When thecompressor 12 is operated, the discharged refrigerant, which isdischarged from the compressor 12, releases the heat to the external airand is condensed in the radiator 13. Thereafter, the flow of thecondensed refrigerant is divided into the following three flows.

That is, the first refrigerant flow passes the metering mechanism 32 andis depressurized. Then, the first refrigerant flow enters the firstevaporator 15. The second refrigerant flow passes the nozzle portion 14a of the ejector 14 and is depressurized. Then, the second refrigerantflow passes the diffuser portion 14 b and is pressurized. Thereafter,the second refrigerant flow enters the first evaporator 15. The thirdrefrigerant flow passes the metering mechanism 17 and is depressurized.Thereafter, the third refrigerant flow passes the second evaporator 18and is then drawn into the suction inlet 14 c of the ejector 14.

Even in the fifth embodiment, the ejector 14 performs the pumpingfunction. That is, the ejector 14 draws the refrigerant present at theoutlet of the second evaporator 18 and mixes the drawn refrigerant withthe refrigerant flow (drive flow), which has passed the nozzle portion14 a, so that the mixed refrigerant is pressurized at the diffuserportion 14 b. Thus, the evaporation pressure of the first evaporator 15is higher than the evaporation pressure of the second evaporator 18, sothat the pressure difference (the refrigerant evaporation temperaturedifference) is created between the evaporation pressure of the secondevaporator 18 and the evaporation pressure of the first evaporator 15.

The flow rate of the refrigerant, which enters the first evaporator 15,can be controlled through the dedicated metering mechanism 32. Thus, theejector 14 does not need to have the flow rate adjusting function foradjusting the flow rate of the first evaporator 15. Similarly, the flowrate of the refrigerant, which enters the second evaporator 18, iscontrolled through the dedicated metering mechanism 17. Thus, thefunction of the ejector 14 is specialized to the pumping function forcreating the pressure difference between the first evaporator 15 and thesecond evaporator 18.

In this way, the configuration of the ejector 14 can be designed tocreate the predetermined pressure difference between the firstevaporator 15 and the second evaporator 18, i.e., to set the flow rateof the refrigerant in the ejector 14 to the predetermined flow rate. Asa result, the vapor compression cycle can be operated at the highefficiency even when the cycle operational condition (e.g., the rpm ofthe compressor, the external air temperature, the subject cooling spacetemperature) varies through a wide range.

Furthermore, the function of the ejector 14 is specialized only to thepumping function, so that it is relatively easy to use the fixed nozzle,which has the fixed passage cross sectional area, as the nozzle portion14 a of the ejector 14. The use of the fixed nozzle allows a reductionin the manufacturing costs of the ejector 14.

SIXTH EMBODIMENT

FIG. 9 shows a sixth embodiment, which is a modification of the fifthembodiment. Specifically, in the sixth embodiment, as shown in FIG. 9,the downstream side (the outlet) of the ejector 14 is connected to thedownstream side (the outlet) of the first evaporator 15. Even with thismodification, the vapor compression cycle can be operated at the highefficiency due to the appropriate design of the configuration of theejector 14.

However, in the sixth embodiment, the refrigerant flow (the drive flow),which has passed the nozzle portion 14 a of the ejector 14, is directlydrawn into the compressor 12 without passing through any evaporator, sothat a problem of liquid refrigerant return to the compressor 12(sometimes referred to as “liquid slugging” of the compressor) possiblyoccurs.

Therefore, it is preferred to apply the sixth embodiment to the casewhere the flow rate of the drive flow in the ejector 14 is relativelysmall, i.e., to the case where the capacity of the second evaporator 18is small.

In the sixth embodiment, when a thermostatic expansion valve, whichcontrols its valve opening degree in a manner that keeps the superheatof the refrigerant at the downstream side of the ejector 14 at thepredetermined value, is used, the liquid refrigerant return from theportion of the refrigerant passage, which is located on the downstreamside of the ejector 14, to the compressor 12 can be more reliablylimited.

SEVENTH EMBODIMENT

FIG. 10 shows a seventh embodiment, which is a modification of the sixthembodiment. Specifically, in the seventh embodiment, with reference toFIG. 10, the ejector 14, the metering mechanism 17 and the secondevaporator 18, which are located within a dotted line frame in thedrawing, are pre-assembled as an integral unit 33.

Two pipe lines, which respectively constitute an inlet passage portionof the first branched passage 16 and a downstream side passage portionlocated downstream of the ejector 14, are provided to the integral unit33. In this way, the known vapor compression refrigeration cycle, whichhas the refrigerant circulation passage 11 (including the compressor 12,the radiator 13, the metering mechanism 32 and the first evaporator 15),can be easily modified to the vapor compression cycle, which includesthe two evaporators 15, 18.

Although the seventh embodiment is the modification of the sixthembodiment, the aspect of the integral unit 33 of the seventh embodimentmay be implemented in the fifth embodiment (FIG. 8).

EIGHTH TO TENTH EMBODIMENTS

In eighth to tenth embodiments, the aspect of the fifth embodiment (FIG.8) is implemented in the vapor compression cycle, which has the threeevaporators 15, 18, 22.

FIG. 11 shows the eighth embodiment, in which the aspect of the fifthembodiment (FIG. 8) is applied to the third embodiment shown in FIG. 5.

FIG. 12 shows the ninth embodiment, in which the downstream side passagelocated downstream of the ejector 14 is connected between the downstreamside of a metering mechanism (a third metering means) 24 and theupstream side of the third evaporator 22 in the eighth embodiment shownin FIG. 11.

FIG. 13 shows the tenth embodiment, in which the downstream side passagelocated downstream of the ejector 14 is directly connected to thesuction inlet of the compressor 12 in the eight embodiment shown in FIG.11. The above point is similar to that of the sixth and seventhembodiments shown in FIGS. 9 and 10.

Even in the eighth to tenth embodiments, the refrigerant evaporationpressure (the refrigerant evaporation temperature) of the firstevaporator 15 becomes the same as that of the third evaporator 22, andthe refrigerant evaporation pressure (the refrigerant evaporationtemperature) of the second evaporator 18 becomes smaller than that ofthe first and the third evaporators 15, 22.

Furthermore, in the eighth to tenth embodiments, the function of theejector 14 can be specialized to the pumping function, so that the vaporcompression cycle can be operated at the high efficiency upon theappropriate designing of the configuration of the ejector 14.

In any of the first to tenth embodiments, the basic cycle structure isthe same as that of the first embodiment, so that the advantages similarto those recited in (1) to (5) in the first embodiment can be achieved.

ELEVENTH EMBODIMENT

An eleventh embodiment will be described with reference to FIGS. 14 to17B. FIG. 14 schematically shows a vapor compression cycle, in which arefrigeration cycle device according to the eleventh embodiment of thepresent invention is implemented and which is suitable for arefrigeration cycle of a vehicle air conditioning system. In the vaporcompression cycle, a refrigerant circulation passage R is provided. Acompressor 101 for drawing and compressing refrigerant is arranged inthe refrigerant circulation passage R. In the refrigerant circulationpassage R, a radiator (a high pressure side heat exchanger) 102 isarranged downstream of the compressor 101. The radiator 102 releases theheat of the high pressure refrigerant, which is discharged from thecompressor 101.

The refrigerant, which is discharged from the radiator 102, is suppliedto a first refrigerant passage 111 of the refrigeration cycle device ofthe present embodiment. The refrigeration cycle device of the presentembodiment includes a box type thermostatic expansion valve 105 and anejector 103. More specifically, a refrigerant inlet 103 a of the ejector103 (i.e., a refrigerant inlet 103 a of a nozzle portion 131 of theejector 103) is air-tightly connected to a downstream side of a meteringportion S1 of the expansion valve 105, i.e., to an outlet of the firstrefrigerant passage 111. Since the expansion valve 105 and the ejector103 are main features of the present embodiment, structures of theexpansion valve 105 and of the ejector 103 will be described in greaterdetail.

In the refrigeration cycle device, a first evaporator 104 is connectedto the refrigerant discharge outlet 103 c of the ejector 103 on thedownstream side of the ejector 103. In the first evaporator 104, therefrigerant, which is discharged from the refrigerant discharge outlet103 c, is evaporated. A refrigerant outlet of the first evaporator 104is connected to a suction inlet of the compressor 101 through a secondrefrigerant passage 112 of the refrigeration cycle device. The flow ofthe refrigerant is divided into two flows at a location (a branchingpoint) between the radiator 102 and the refrigeration cycle device(i.e., the expansion valve 105 and the ejector 103). One of the twodivided flows is conducted through a refrigerant circulation passage R1and is supplied to an inlet of the first refrigerant passage 111 of therefrigeration cycle device. The other one of the two divided flows isconducted through a branched passage R2 and is supplied to a refrigerantsuction inlet 103 b of the refrigeration cycle device (morespecifically, the ejector 103).

Next, the details of the structures of the expansion valve 105 and ofthe ejector 103 will be described. FIG. 15 is a cross sectional view ofthe expansion valve 105 of the present embodiment. The expansion valve105 is arranged in the refrigerant passage between the radiator 102 andthe ejector 103, i.e., is arranged on the upstream side of a nozzleportion 131 of the ejector 103. The expansion valve 105 depressurizesand expands the high pressure refrigerant, which is discharged from theradiator 102, to two-phase refrigerant of a gas and liquid mixture. Theexpansion valve 105 of the present embodiment has the structure similarto that of a know box type thermostatic expansion valve. A valve openingdegree of the expansion valve 105 is controlled to keep the refrigerantsuperheat in a predetermined range (e.g., 0.1 degrees to 10 degrees) atthe refrigerant outlet of the first evaporator 104.

The expansion valve 105 includes a valve block (a valve main body) D, anelement arrangement E, a heat conducting portion 120, a conducting rod125 and a ball valve element 110. The valve block D is made of, forexample, aluminum and is formed into a generally rectangularparallelepiped body. Furthermore, the valve block D includes the firstrefrigerant passage 111 and the second refrigerant passage 112.

The first refrigerant passage 111 includes an inflow port (refrigerantinlet) 111 a, an outflow port (refrigerant outlet) 111 b and acommunication hole 111 c. The inflow port 111 a is connected to theoutlet of the radiator 102. The outflow port 111 b is connected to arefrigerant inlet 103 a of the ejector 103. The communication hole 111 ccommunicates between the inflow port 111 a and the outflow port 111 b. Aconical valve seat surface 111 d is provided to an inlet of thecommunication hole 111 c on the inflow port 111 a side of thecommunication hole 111 c. The second refrigerant passage 112 includes aninflow port (refrigerant inlet) 112 a, an outflow port (refrigerantoutlet) 112 b and a communication passage 112 c. The inflow port 112 ais connected to the outlet of the evaporator 104. The outflow port 112 bis connected to the suction inlet of the compressor 101. Thecommunication passage 112 c communicates between the inflow port 112 aand the outflow port 112 b and also communicates with the heatconducting portion 120.

The element arrangement E includes a diaphragm 113, a receiving portion114 and a cover portion 115. The diaphragm 113 is made of a flexiblethin metal plate. The receiving portion 114 holds the diaphragm 113. Theelement arrangement E is screwed and secured to a top of the valve blockD through a packing 116. The receiving portion 114 and the cover portion115 are connected together by, for example, TIG welding. The diaphragm113 and the cover portion 115 form a diaphragm chamber 117.

Saturated gas, which is of the same type as the refrigerant gas is usedin the refrigeration cycle, is filled in the diaphragm chamber 117. Athrough hole for filling the saturated gas into the diaphragm chamber117 penetrates through the cover portion 115. After filling of thesaturated gas into the diaphragm chamber 117, a plug 118 is fitted tothe through hole of the cover portion 115 to air-tightly close it. Eachcomponent (the diaphragm 113, the receiving portion 114, the coverportion 115 and the plug 118) of the element arrangement E is made of acommon metal material (e.g. stainless steel), which serves as a firstmaterial.

The heat conducting portion 120 is made of a metal material (e.g.,aluminum or brass), which serves as a second material and shows arelatively high thermal conductivity that is higher than that of thefirst material, and is formed into a cylindrical body. An upper surfaceof the cylindrical body of the heat conducting portion 120 is urgedupwardly by an urging force (described later) and is closely engagedwith a lower surface of the diaphragm 113. A change in the temperatureof the refrigerant (gas phase refrigerant evaporated in the evaporator104), which flows in the second refrigerant passage 112, is conducted tothe diaphragm 113 through the heat conducting portion 120. Furthermore,a lower surface of the cylindrical body of the heat conducting portion120 is engaged with the conducting rod 125 to conduct displacement ofthe diaphragm 113 to the ball valve element 110 in cooperation with theconducting rod 125.

The conducting rod 125 is arranged under the heat conducting portion 120and is slidably held by the valve block D. The conducting rod 125 isengaged with the lower surface of the heat conducting portion 120 at itstop end. Furthermore, the conducting rod 125 extends through the secondrefrigerant passage 112 (the communication passage 112 c) in thevertical direction and is inserted in to the communication hole 111 c ofthe first refrigerant passage 111. A lower end of the conducting rod 125is engaged with a top surface of the ball valve element 110, which isurged against the conical seat surface 111 d by a spring 122. In aportion of the valve block D between the first refrigerant passage 111and the second refrigerant passage 112, an O-ring (a seal portion) 119is provided to the conducting rod 125, which is vertically slidablyreceived in the valve block D.

As shown in FIG. 15, the ball valve element 110 is provided to the inletof the communication hole 111 c and is held between the conducting rod125 and a valve receiving member 121. When the ball valve element 110 isseated against the seat surface 111 d, the ball valve element 110 closesthe communication hole 111 c. When the ball valve element 110 is liftedaway from the seat surface 111 d, the ball valve element 110 opens thecommunication hole 111 c. In FIG. 15, the ball valve element 110 isstationary held in the position where the urging force for downwardlyurging the diaphragm 113 (the pressure of the diaphragm chamber 117—thepressure of the refrigerant vapor applied to the lower side of thediaphragm 113) and the load of the spring 122, which urges the ballvalve element 110 in the upward direction in FIG. 15 through the valvereceiving member 121, are balanced.

The spring 122 is arranged between the valve receiving member 121 and anadjusting screw 123, which is installed to the lower end of the valveblock D. The spring 122 urges the ball valve element 110 in the upwarddirection (the direction for reducing the valve opening degree) in FIG.15 through the valve receiving member 121. The adjusting screw 123adjusts the valve opening pressure of the ball valve element 110 (theload of the spring 122 that urges the ball valve element 110) and isthreadably engaged with the lower end of the valve block D through anO-ring 124.

Next, operation of the expansion valve 105 will be described. The flowrate of the refrigerant, which passes the communication hole 111 c, isdetermined based on the valve opening degree of the ball valve element110, i.e., based on the position (the lift amount) of the ball valveelement 110 relative to the seat surface 111 d. The ball valve element110 is moved to a balanced position where the pressure of the diaphragmchamber 117, which urges the diaphragm 113 in the downward direction inFIG. 15, the load of the spring 122, which urges the diaphragm 113 inthe upward direction in FIG. 15, and the low pressure in the cycle (thepressure of the refrigerant vapor applied to the lower side of thediaphragm 113) are balanced.

When the temperature of the vehicle passenger compartment is increasedfrom the stable state where the vapor pressure is stable, and therebythe refrigerant is rapidly evaporated in the evaporator 104, thetemperature (the superheat) of the refrigerant vapor at the outlet ofthe evaporator 104 is increased. In this way, the change in thetemperature of the refrigerant vapor, which flows in the secondrefrigerant passage 112, is conducted to the sealed gas, which is sealedin the diaphragm chamber 117, through the heat conducting portion 120and the diaphragm 113. When the temperature of the sealed gas in thediaphragm chamber 117 is increased, the pressure of the diaphragmchamber 117 is increased.

Thus, the diaphragm 113 is urged and is moved in the downward directionin FIG. 15. As a result, the valve opening degree is increased, and theflow rate of the refrigerant supplied to the evaporator 104 isincreased. In contrast, when the temperature of the passengercompartment is decreased, and the superheat of the outlet of theevaporator 104 is decreased, the change in the temperature of therefrigerant vapor, which flows in the second refrigerant passage 112, isconducted to the sealed gas of the diaphragm chamber 117. Due to thedecrease in the temperature of the sealed gas, the pressure of thediaphragm chamber 117 is decreased.

As a result, when the diaphragm 113 is pushed in the upward direction inFIG. 15, and thereby the ball valve element 110 is moved in the upwarddirection in FIG. 15, the valve opening degree is decreased. Therefore,the flow rate of the refrigerant, which is supplied to the evaporator104, is decreased. Therefore, during the normal cycle operation, thevalve opening degree is controlled to make the temperature (thesuperheat) of the refrigerant vapor, for example, about 5 degreesCelsius and thereby to control the flow rate of the refrigerant, whichflows in the communication hole 111 c.

FIG. 16 is a cross sectional view of the structure of the ejector 103 ofthe present embodiment, and FIGS. 17A and 17B are descriptive views fordescribing the advantages of the ejector 103 of FIG. 16. The ejector 103depressurizes and expands the refrigerant, which is supplied from theradiator 102 through the refrigerant inlet 103 a via the firstrefrigerant passage 111 (the first metering portion S1 in FIG. 14) ofthe expansion valve 105, so that the ejector 103 draws the gas phaserefrigerant, which is evaporated in the second evaporator 106, throughthe refrigerant suction inlet 103 b. Furthermore, the ejector 103converts the expansion energy of the refrigerant to the pressure energyof the refrigerant and discharges the refrigerant from the refrigerantdischarge outlet 103 c to increase the suction pressure of thecompressor 101.

The ejector 103 includes the nozzle portion 131, the mixing portion 132and the diffuser portion 133. The nozzle portion 131 isentropicallydepressurizes and expands the high pressure refrigerant, which issupplied through the refrigerant inlet 103 a, by converting the pressureenergy of the high pressure refrigerant, which is supplied through therefrigerant inlet 103 a, into the velocity energy. Through use of theentraining action of the high velocity refrigerant flow (drive flow),which is discharged from the nozzle portion 131, the mixing portion 132draws the gas phase refrigerant, which is evaporated in the secondevaporator 106, through the suction inlet 103 b. Then, the mixingportion 132 mixes the drawn refrigerant, which is drawn from the secondevaporator 106, and the discharged refrigerant, which is discharged fromthe nozzle portion 131. The diffuser portion 133 further mixes the drawnrefrigerant, which is drawn from the second evaporator 106, and thedischarged refrigerant, which is discharged from the nozzle portion 131.Also, at the same time, the diffuser portion 133 converts the velocityenergy of the refrigerant to the pressure energy of the refrigerant toincrease the pressure of the refrigerant.

At this time, in the mixing portion 132, the drive flow and the drawnflow are mixed such that the sum of the kinetic energy of the drive flowand kinetic energy of the drawn flow is conserved. Thus, even in themixing portion 132, the pressure (the static pressure) of therefrigerant is increased. In the diffuser portion 133, the passage crosssectional area is progressively increased to convert the velocity energy(dynamic pressure) of the refrigerant to the pressure energy (staticpressure). Thus, in the ejector 103, the refrigerant pressure isincreased in both of the mixing portion 132 and the diffuser portion133. Hereinafter, the mixing portion 132 and the diffuser portion 133will be collectively referred to as a pressurizing portion.

In the present embodiment, a Laval nozzle, which has a throat (a secondmetering portion) S2 that has the smallest passage cross sectional areain the Laval nozzle, is used to accelerate the velocity of therefrigerant, which is discharged from the nozzle portion 131, to a sonicvelocity or higher velocity. However, it should be understood that atapered nozzle can be used in place of the Laval nozzle. In the presentembodiment, the passage cross sectional area of the mixing portion 132before the diffuser portion 133 is constant. Alternatively, the passagecross sectional area of the mixing portion 132 can be tapered to have anincreasing passage cross sectional area, which increases toward thediffuser portion 133.

The high pressure refrigerant, which is cooled in the radiator 102, isisentropically depressurized to the two-phase refrigerant (mixture ofgas and liquid) range. Thereafter, the refrigerant is isentropicallydepressurized and is expanded by the nozzle portion 131 of the ejector103 and is supplied to the mixing portion 132 at the sonic velocity orhigher velocity. Therefore, the refrigerant is boiled once in theexpansion valve 105 and is expanded at the inlet of the nozzle portion131 to recover the pressure. In this way, the refrigerant can be boiledin the nozzle portion 131 while the boiling nucleus is kept generated.Thus, the boiling of the refrigerant in the nozzle portion 131 ispromoted, and the liquid refrigerant droplets are atomized to improvethe ejector efficiency ηe (FIG. 17A).

In the present embodiment, chlorofluorocarbon is used as the refrigerantto keep the high pressure side refrigerant pressure (i.e., the pressureof the refrigerant supplied to the nozzle portion 131) equal to or lessthan the critical pressure of the refrigerant. Due to the pump action,which utilizes the entraining action of the high velocity refrigerantthat is supplied to the mixing portion 132, the refrigerant, which isevaporated in the second evaporator 106, is drawn into the mixingportion 132. Thus, the low pressure side refrigerant is circulatedthrough the second evaporator 106 and the pressurizing portion 132, 133of the ejector 103 in this order.

In contrast, the refrigerant (the drawn flow), which is drawn from thesecond evaporator 106, and the refrigerant (the drive flow), which isdischarged from the nozzle portion 131, are mixed in the mixing portion132, and the dynamic pressure of the mixed refrigerant is converted intothe static pressure in the diffuser portion 133. Thereafter, the mixedrefrigerant is discharged from the diffuser portion 133. Therefore, inthe present embodiment, the nozzle efficiency and the ejector efficiencyare increased while achieving the sufficient refrigeration capacity, andit is possible to correspond to a wide range of the load change.

In the first evaporator 104, heat is exchanged between the refrigerantand the air to be discharged into the passenger compartment, so that therefrigerant is evaporated upon absorbing the heat. In this way, thecooling capacity is implemented. Furthermore, in the second evaporator106, heat is exchanged between the refrigerant and the air in theinterior of the refrigerator, so that the refrigerant is evaporated uponabsorbing the heat. In this way, the cooling capacity is implemented.

Next, operation of the present embodiment will be described withreference to the above structure. When the compressor 101 is operated,the refrigerant is compressed in the compressor 101, so that the hightemperature and high pressure refrigerant is discharged from thecompressor 101 and is supplied to the radiator 102. In the radiator 102,the high temperature refrigerant releases the heat to the external air,which is external to the vehicle passenger compartment. That is, in theradiator 102, the refrigerant is cooled by the external air and iscondensed to the liquid state.

The liquid phase refrigerant, which is outputted from the radiator 102,is divided into the refrigerant circulation passage R1 and the branchedpassage R2. In the refrigerant circulation passage R1, the refrigerantis supplied from the first refrigerant passage 111 of the refrigerationcycle device to the ejector 103 and is depressurized in the nozzleportion 131. That is, in the nozzle portion 131, the pressure energy ofthe refrigerant is converted into the velocity energy. The refrigerant,which is discharged from the outlet of the nozzle portion 131 at thehigh velocity, draws the gas phase refrigerant, which is evaporated inthe second evaporator 106, through the suction inlet 103 b due to theadiabatic heat drop that occurs at the time of discharging therefrigerant from the nozzle portion 131.

The discharged refrigerant, which is discharged from the nozzle portion131, and the drawn refrigerant, which is drawn from the secondevaporator 106, are mixed, and the mixed refrigerant is supplied to thediffuser portion 133. At this time, the expansion energy of therefrigerant is converted into the pressure energy, so that the pressureof the refrigerant is increased. The refrigerant, which is dischargedfrom the ejector 103, is supplied to the first evaporator 104. In thefirst evaporator 104, the refrigerant absorbs the heat from the air tobe discharged into the vehicle passenger compartment. In other words, inthe first evaporator 104, the refrigerant is heated by the interior airof the vehicle passenger compartment and is evaporated.

The evaporated gas phase refrigerant is supplied to the compressor 101through the second refrigerant passage 112 of the refrigeration cycledevice. In the branched passage R2, the other divided refrigerant flowis supplied to the second evaporator 106. In the second evaporator 106,the refrigerant absorbs the heat from the interior air of therefrigerator. In other words, in the second evaporator 106, therefrigerant is heated by the interior air of the refrigerator and isevaporated. The evaporated refrigerant is drawn through the suctioninlet 103 b of the ejector 103.

Next, the characteristic features and advantages of the presentembodiment will be described. The refrigeration cycle device of thepresent embodiment includes the box type thermostatic expansion valve105 and the ejector 103. The expansion valve 105 forms the firstmetering portion S1 to serve as the depressurizing means fordepressurizing the high pressure refrigerant. Furthermore, the expansionvalve 105 adjusts the flow rate of the refrigerant, which passes thefirst refrigerant passage 111, based on the superheat of therefrigerant, which passes the first refrigerant passage 111. The ejector103 includes the nozzle portion 131 and the pressurizing portion 132,133. The nozzle portion 131 forms the second metering portion S2 anddepressurizes and expands the refrigerant by converting the pressureenergy of the high pressure refrigerant, which is supplied through theinlet 103 a, into the velocity energy. The pressurizing portion 132, 133draws the gas phase refrigerant from the suction inlet 103 b through useof the high velocity refrigerant, which is discharged from the nozzleportion 131. The pressuring portion 132, 133 converts the velocityenergy to the pressure energy while mixing the discharged refrigerant,which is discharged from the nozzle portion 131, and the drawnrefrigerant, which is drawn from the suction inlet 103 b, so that thepressure of the mixed refrigerant is increased by the pressurizingportion 132, 133. The refrigerant inlet 103 a of the ejector 103 isair-tightly connected to the downstream side of the metering portion S1of the box type thermostatic expansion valve 105.

FIG. 14 is the schematic view of the vapor compression cycle, whichincludes the refrigeration cycle device of the eleventh embodiment. Withrespect to the previously proposed refrigeration cycle, in the vaporcompression cycle of the present embodiment, the ejector 103, whichincludes the nozzle portion 131 and the pressurizing portion 132, 133,is placed between the expansion valve 105 and the first evaporator 104and is connected to the expansion valve 105, so that the ejector 103draws and pressurizes the refrigerant, which is supplied from the secondevaporator 106. Therefore, the first and second evaporators 104, 106 areoperated at different temperature ranges. At this time, the ejector 103is easily and detachably connected to the expansion valve 105, so thatthe variable ejector having the simple structure is provided.

Furthermore, in order to correspond to the load change, the superheat atthe outlet of the first evaporator 104 is sensed. At the time of thehigh load operation, the superheat becomes excessively large, andthereby the expansion valve 105 is opened. In contrast, at the time ofthe low load operation, the expansion valve 105 is closed. Therefore,the flow rate of the refrigerant is adjusted. Furthermore, the nozzleportion 131 converts the pressure energy to the velocity energy.However, when the two-phase refrigerant of the mixture of the gas andliquid is used, the nozzle efficiency is decreased due to the delay inthe boiling of the refrigerant in the second metering portion S2. Toaddress this issue, the boiling nucleus is initially generated in theexpansion valve 105 by the depressurization to improve the ejectorefficiency (the nozzle efficiency).

Furthermore, a predetermined space is interposed between the firstmetering portion S1 and the second metering portion S2. In the casewhere the nozzle efficiency is improved by initially generating theboiling nucleus in the expansion valve 105, the space between the firstmetering portion S1, which is implemented by the expansion valve 105,and the second metering portion S2, which is implemented by the nozzlethroat, contributes to the improved performance. In this way, throughthe simple assembly of the expansion valve 105 with the ejector 103, andthe provision of the predetermined space between the first meteringportion S1 and the second metering portion S2, the high ejectorefficiency can be achieved.

Furthermore, the expansion valve 105 and the ejector 103 are connectedto each other such that the center axis of the expansion valve 105 isperpendicular to the center axis of the ejector 103. In this way, thedirection of the suction inlet 103 b of the ejector 103 can be freelyselected within 360 degrees to provide more freedom at the time ofmounting the ejector 103.

Furthermore, the box type expansion valve 105 includes the firstrefrigerant passage 111, the second refrigerant passage 112, the ballvalve element 110, the element arrangement E and the heat conductingportion 120. The first refrigerant passage 111 is connected to the inletof the first evaporator 104. The second refrigerant passage 112 isconnected to the outlet of the first evaporator 104. The ball valveelement 110 changes the flow rate of the refrigerant in the firstrefrigerant passage 111. In the element arrangement E, the diaphragm 113is held, i.e., is clamped between the receiving portion 114 and thecover portion 115, and the saturated gas is sealed in the diaphragmchamber 117 between the diaphragm 113 and the cover portion 115.Furthermore, the diaphragm 113, the receiving portion 114 and the coverportion 115 are made of the common material. The element arrangement Eis detachably connected to the valve block D. The heat conductingportion 120 is made of the different material, which shows the thermalconductivity that is higher than that of the element arrangement E. Theheat conducting portion 120 conducts the temperature change of therefrigerant, which flows in the second refrigerant passage 112, to thediaphragm 113. Furthermore, the heat conducting portion 120 conducts thedisplacement of the diaphragm 113 to the ball valve element 110. Theflow rate of the refrigerant, which flows in the first refrigerantpassage 111, is adjusted based on the displacement of the ball valveelement 10.

The above structure is of the previously proposed box type expansionvalve 105. With the above structure, through the combination of thepreviously proposed devices, the manufacturing costs can be minimized.Furthermore, variations of the above structure can be implemented at therelatively low costs by appropriately combining the previously proposeddevices.

Furthermore, the above vapor compression type refrigeration cycle, whichtransfers the heat of the lower temperature side to the highertemperature side, includes the compressor 101, the radiator 102, therefrigeration cycle device 103, 105, the first evaporator 104, thebranched passage R2 and the second evaporator 106. The compressor 101compresses the refrigerant. The radiator 102 releases the heat from thehigh pressure refrigerant, which is discharged from the compressor 101.The refrigeration cycle device supplies the refrigerant, which isoutputted from the radiator 102, to the first refrigerant passage 111.The outlet of the first evaporator 104 is connected to the suction inletof the compressor 101 through the second refrigerant passage 112. Thefirst evaporator 104 evaporates the refrigerant, which is dischargedfrom the outlet 103 c of the refrigeration cycle device. The branchedpassage R2 branches the refrigerant flow at the point (branching point)between the radiator 102 and the refrigeration cycle device and conductsit to the suction inlet 103 b. The second evaporator 106 is arranged inthe branched passage R2 and evaporates the refrigerant.

With the above structure, the ejector 103 is easily detachable relativeto the expansion valve 105. Thus, the vapor compression cycle can bemade with the simple structure. Furthermore, in the case where thesecond evaporator 106 is not used, the simple normal expansion valvecycle can be made by simply removing the ejector 103 and the secondevaporator 106.

Furthermore, in the above embodiment, the refrigerant can be one of thechlorofluorocarbon refrigerant, hydrocarbon (HC) refrigerant and thecarbon dioxide refrigerant. The chlorofluorocarbon is a general name ofan organic compound, which is made from carbon, fluorine, chlorine andhydrogen. The chlorofluorocarbon has been widely used as therefrigerant. The chlorofluorocarbon refrigerant includeshydrochlorofluorocarbon (HCFC) refrigerant, hydrofluorocarbon (HFC)refrigerant and the like and is called as the alternative forchlorofluorocarbon, which is used to limit damage of the ozone shield.

The HC refrigerant is the natural refrigerant material, which includeshydrogen and carbon. Examples of the HC refrigerant include R600a(isobutene) and R290 (propane). Accordingly, any one of thechlorofluorocarbon refrigerant, the hydrocarbon refrigerant and thecarbon dioxide refrigerant can be used as the refrigerant of the presentembodiment.

TWELFTH EMBODIMENT

FIG. 18A is a partial cross sectional view of a refrigeration cycledevice according to a twelfth embodiment of the present invention, andFIG. 18B is a view seen in a direction of XVIIIB in FIG. 18A. In theeleventh embodiment, the expansion valve 105 and the ejector 103 areconnected to each other such that the center axis of the expansion valve105 is perpendicular to the center axis of the ejector 103. In thetwelfth embodiment, the expansion valve 105 and the ejector 103 areconnected to each other such that the center axis of the expansion valve105 is parallel to the center axis of the ejector 103. In this way, thedirection of the refrigerant discharge outlet 103 c of the ejector 103can be freely selected within 360 degrees to provide more freedom at thetime of mounting the ejector 103.

The first to twelfth embodiments can be modified as follows.

(1) In the first embodiment, the present invention is implemented in thevehicle air conditioning and refrigerating system. Alternatively, boththe first evaporator 15, which has the higher refrigerant evaporationtemperature, and the second evaporator 18, which has the lowerrefrigerant evaporation temperature, can be used to cool differentregions (e.g., the vehicle front seat side region and the vehicle rearseat side region) of the vehicle passenger compartment.

(2) In the first embodiment, both the first evaporator 15, which has thehigher refrigerant evaporation temperature, and the second evaporator18, which has the lower refrigerant temperature, can be used to cool theinterior of the refrigerator. More specifically, the first evaporator15, which has the higher refrigerant evaporation temperature, can beused to cool the interior of the chillroom of the refrigerator, and thesecond evaporator 18, which has the lower refrigerant evaporationtemperature, can be used to cool the interior of the freezing room ofthe refrigerator.

(3) The vapor compression cycle of the present invention can be appliedto a vapor compression cycle, such as a heat pump of a water heater.

(4) Although the type of the refrigerant is no specified in the first totenth embodiments, the refrigerant can be any suitable refrigerant, suchas, chlorofluorocarbon, hydrocarbon (HC) alternatives forchlorofluorocarbon, carbon dioxide, which is applicable to both asupercritical vapor compression cycle and a sub-critical vaporcompression cycle.

(5) In the first embodiment, the gas-liquid separator is not used.Alternatively, the gas-liquid separator may be provided on the upstreamside of the first evaporator 15 to provide only the liquid phaserefrigerant to the first evaporator 15. Further alternatively, thegas-liquid separator may be provided to the upstream side of thecompressor 12 to provide only the gas phase refrigerant to thecompressor 12. Furthermore, a receiver may be provided on the downstreamside of the radiator 13. The receiver separates the liquid phaserefrigerant from the gas phase refrigerant and supplies only the liquidphase refrigerant to its downstream side.

(6) In the first to fourth embodiments, the first flow rate controlvalve 17 is provided on the upstream side of the second evaporator 18.In a case where a change in the thermal load of the second evaporator 18is relatively small, a fixed metering device, such as a capillary tube,which has an aperture of a fixed size, can be used as the first flowrate control valve 17.

Furthermore, when the fixed metering device and the solenoid valve areintegrated together as the first flow rate control valve 17, it ispossible to provide a metering mechanism, in which the flow rate controlfunction of the fixed metering device and the flow passage closing(shutting off) function are combined.

Furthermore, the first flow rate control valve 17 can be a meteringdevice (e.g., an expansion valve), which has a mechanism to control anopening degree of its aperture based on the sensed superheat at theoutlet of the evaporator.

Furthermore, in the second and third embodiments, the first flow ratecontrol valve 17 is separated from the second solenoid valve 20, and thesecond flow rate control valve 24 is separated from the third solenoidvalve 28. Alternatively, in place of the combination of the first flowrate control valve 17 and the second solenoid valve 20 and/or thecombination of the second flow rate control valve 24 and the thirdsolenoid valve 28, a metering valve(s) with the flow passage closing(shutting off) function, in which the flow rate control valve and thesolenoid valve are integrated, can be used.

(7) In the first to fourth embodiments, the variable displacementcompressor is used as the compressor 12, and the volume of the variabledisplacement compressor 12 is controlled by the ECU 25 to control therefrigerant discharge rate. Alternatively, a fixed displacementcompressor may be used as the compressor 12. In such a case, on- andoff-operations of the fixed displacement compressor 12 are controlled byan electromagnetic clutch, and a ratio of an on-operation time periodand an off-operation time period of the compressor 12 is controlled tocontrol the refrigerant discharge rate of the compressor 12.

Furthermore, in a case where an electric compressor is used, therefrigerant discharge rate of the electric compressor 12 can becontrolled by controlling the rpm of the electric compressor 12.

(8) In the first to tenth embodiments, if the ejector 14 is a flow ratevariable ejector, in which a cross sectional area of the refrigerantflow passage of the nozzle portion 14 a is variable based on the sensedsuperheat at the outlet of the first evaporator 15, the dischargedrefrigerant pressure (the flow rate of the refrigerant to be drawn intothe ejector 14) can be controlled.

Thus, in each of the multiple evaporator operating modes of the secondembodiment, the first and second evaporator operating mode and the firstto third evaporator operating mode of the third embodiment, the flowrate of the refrigerant, which flows through the second evaporator 18,can be more precisely controlled.

(9) In the first to tenth embodiments, the multiple evaporators (e.g.,the first and second evaporators 15, 18) can be integrally assembled asa single unit.

(10) In the eleventh and twelfth embodiments, the present invention isimplemented in the vehicle air conditioning system. However, the presentinvention is not limited to the vehicle air conditioning system. Forexample, the present invention can be implemented in any other vaporcompression type cycle, such as a heat pump cycle of a water heater.Furthermore, in the eleventh and twelfth embodiments, the first andsecond evaporators 104, 106 have the two different refrigerationcapacities, respectively. Alternatively, three or more evaporators canbe provided to have three or more different refrigeration capacities.

Furthermore, a receiver can be arranged downstream of the radiator 102in the eleventh and twelfth embodiments. Also, a fixed ejector, in whichthe second metering portion S2 of the nozzle portion 131 is stationary,may be used in place of the ejector 103 of the eleventh and twelfthembodiments. Furthermore, in the eleventh and twelfth embodiments, thetwo evaporators 104, 106 of different refrigeration capacities areseparately constructed. Alternatively, these evaporators 104, 106 can beformed integrally, as discussed in the following embodiments.

THIRTEENTH EMBODIMENT

FIGS. 19 and 20 show a thirteenth embodiment of the present invention.Specifically, FIG. 19 shows an exemplary case where a vapor compressioncycle 210 of the thirteenth embodiment is applied to a vehicularrefrigeration cycle. In the cycle 210 of the present embodiment, acompressor 211, which draws and compresses refrigerant, is driven by avehicle drive engine (not shown) through, for example, a solenoid clutch212, a belt and the like.

The compressor 211 may be a variable displacement compressor or a fixeddisplacement compressor. In the case of the variable displacementcompressor, a refrigerant discharge rate is adjusted by changing itsdisplacement. In the case of the fixed displacement compressor, arefrigerant discharge rate is adjusted by varying its operating ratethrough repeated connection and disconnection of the solenoid clutch212. Furthermore, when an electric compressor is used as the compressor211, a refrigerant discharge rate can be adjusted by adjusting arotational speed of an electric motor.

A radiator 213 is provided on a refrigerant outlet side of thecompressor 211. The radiator 213 exchanges heat between the highpressure refrigerant, which is discharged from the compressor 211, andthe external air (external air supplied from outside of the vehicle),which is blown toward the radiator 213 by a cooling fan (not shown), sothat the high pressure refrigerant is cooled.

In a case where an ordinary fluorocarbon refrigerant is used as therefrigerant of the cycle 210, the cycle 210 becomes a sub-criticalpressure cycle, in which its high pressure does not exceed a criticalpressure. Thus, the radiator 213 acts as a condenser, which condensesthe refrigerant. In contrast, in a case where another type ofrefrigerant, such as a carbon dioxide (CO₂) refrigerant, which has itshigh pressure exceeding the critical pressure, is used, the cycle 210becomes a super-critical cycle. Thus, in such a case, the refrigerantradiates heat in a super-critical state without condensation of therefrigerant.

An ejector 214 is arranged on a downstream side of the radiator 213 inthe refrigerant flow direction in the cycle 210. The ejector 214 servesas a depressurizing means for depressurizing the refrigerant and isformed as a momentum-transporting pump, which performs fluidtransportation by entraining action of discharged high velocity workingfluid (see JIS Z 8126 Number 2.1.2.3).

The ejector 214 includes a nozzle portion 214 a and a refrigerantsuction inlet 214 b. The nozzle portion 214 a reduces a cross sectionalarea of the refrigerant passage, which conducts the high pressurerefrigerant discharged from the radiator 213, to isentropicallydepressurize and expand the high pressure refrigerant. The suction inlet214 b is arranged in a space, in which a refrigerant outlet of thenozzle portion 214 a is located. The suction inlet 214 b draws gas phaserefrigerant supplied from a second evaporator 218 described below.

Furthermore, a mixing portion 214 c is provided on a downstream side ofthe nozzle portion 214 a and of the suction inlet 214 b in therefrigerant flow direction. The mixing portion 214 c mixes the highvelocity refrigerant flow, which is outputted from the nozzle portion214 a, with the drawn refrigerant, which is drawn through the suctioninlet 214 b. A diffuser portion 214 d, which serves as a pressurizingportion, is arranged downstream of the mixing portion 214 c in therefrigerant flow direction. The diffuser portion 214 d is formed toprogressively increase a cross sectional area of its refrigerant passagetoward its downstream end. Thus, the diffuser portion 214 d deceleratesthe refrigerant flow and increases the refrigerant pressure, i.e., thediffuser portion 214 d converts the velocity energy of the refrigerantto the pressure energy.

A first evaporator 215 is connected to a downstream side of the diffuserportion 214 d of the ejector 214, and a downstream side of the firstevaporator 215 is connected to an inlet side of the compressor 211.

A branched refrigerant passage (or simply referred to as a branchedpassage) 216 is branched from a branch point, which is located on anupstream side of the ejector 214 (an intermediate point between theradiator 213 and the ejector 214), in the cycle 210. A downstream sideof the branched passage 216 is connected to the suction inlet 214 b ofthe ejector 214. In FIG. 19, numeral Z indicates the branch point of thebranched passage 216.

A metering mechanism (or a flow rate control valve serving as a meteringmeans) 217 is arranged in the branched passage 216. The secondevaporator 218 is arranged on a downstream side of the meteringmechanism 217. The metering mechanism 217 is a depressurizing means foradjusting a flow rate of the refrigerant supplied toward the secondevaporator 218. Specifically, the metering mechanism 217 may be a fixedchoke or throttle, such as an orifice. Alternatively, the meteringmechanism 217 may be an electric control valve, which is driven by anelectric actuator to adjust a valve opening degree (a passage openingdegree) of the control valve.

In the present embodiment, the two evaporators 215, 218 are constructedintegrally (assembled integrally or formed integrally) such that the twoevaporators 215, 218 are received in a single case 219. A commonelectric blower 220 blows the air (air to be cooled) to an air passagein the case 219, as indicated by an arrow A in FIG. 19, so that theblown air is cooled by the two evaporators 215, 218.

The cooled air, which is cooled by the two evaporators 215, 218, issupplied to a common subject cooling space 221, so that the commonsubject cooling space 221 is cooled by the two evaporators 215, 218.Among the two evaporators 215, 218, the first evaporator 215, which isconnected to a main flow passage located on a downstream side of theejector 214, is arranged on an upstream side in the air flow A, and thesecond evaporator 218, which is connected to the suction inlet 214 b ofthe ejector 214, is arranged on a downstream side in the air flow A.

In a case where the cycle 210 of the present embodiment is applied to arefrigeration cycle of a vehicle air conditioning system, a passengercompartment of the vehicle becomes the subject cooling space 221. In acase where the cycle 210 of the present embodiment is applied to arefrigeration cycle of a freezer and/or refrigerator (or simplyindicated as “freezer/refrigerator”) vehicle, a freezer/refrigeratorspace of the freezer/refrigerator vehicle becomes the subject coolingspace 221.

Next, a specific example of the integrated structure of the twoevaporators 215, 218 will be described with reference to FIG. 20. In theexample of FIG. 20, the two evaporators 215, 218 are integrated togetheras a single evaporator structure. Thus, the first evaporator 215constitutes the upstream side section of the single evaporatorstructure, which is located on the upstream side in the air flow A.Furthermore, the second evaporator 218 constitutes the downstream sidesection of the single evaporator structure, which is located on thedownstream side in the air flow A.

The structure of the first evaporator 215 and the structure of thesecond evaporator 218 are basically the same. Thus, each of the firstand second evaporators 215, 218 has a heat exchange core 215 a, 218 aand upper and lower tanks 215 b, 215 c, 218 b, 218 c. The upper andlower tanks 215 b, 215 c, 218 b, 218 c are arranged on upper and lowersides, respectively, of the heat exchange core 215 a, 218 a.

The heat exchange core 215 a, 218 a has a stack structure that includesa plurality of vertically extending tubes 222 and a plurality of fins223. Each fin 223 is connected between corresponding two of the tubes222. In FIG. 20, only the tubes 222 and the fins 223 of the heatexchange core 215 a of the first evaporator 215, which is located on theupstream side in the air flow A, are depicted, while the tubes 222 andthe fins 223 of the heat exchange core 218 a of the second evaporator218 are not depicted for the sake of simplicity. However, it should benoted that the heat exchange cores 215 a, 218 a have basically the samestructure, as noted above.

The tubes 222 constitute the refrigerant passages and are made asgenerally planar tubes, each of which is planar, i.e., is generallyflattened in the air flow direction A. The fins 223 are made ascorrugated fins, each of which is formed by bending a thin platematerial into a wavy form and is joined to planar outer surfaces of thecorresponding tubes 222 to increase a heat transfer surface area forexchanging heat with the air.

The tubes 222 and the fins 223 are alternately stacked one after anotherin a left-right direction of the heat exchange core 215 a, 218 a. Twoside plates 215 d, 215 e, 218 d, 218 e are arranged at opposed ends,respectively, of the heat exchange core 215 a, 218 a, which are opposedto each other in a stacking direction of the tubes 222 and the fins 223(i.e., in the left-right direction of the heat exchange core 215 a, 218a) to reinforce the heat exchange core 215 a, 218 a. The side plates 215d, 215 e, 218 d, 218 e are connected to the left and right outermostcorrugated fins 223, respectively, and are also connected to the upperand lower tanks 215 b, 215 c, 218 b, 218 c.

The upper and lower tanks 215 b, 215 c of the first evaporator 215 formsa refrigerant passage space, which is independent from a refrigerantpassage space, which is formed by the upper and lower tanks 218 b, 218 cof the second evaporator 218. The upper and the lower tanks 215 b, 215 cof the first evaporator 215 have tube engaging holes (not shown), towhich upper and lower ends of the tubes 222 of the heat exchange core215 a are connected in such a manner that the upper and lower ends ofthe tubes 222 are communicated with interior spaces of the tanks 215 b,215 c.

Similarly, the upper and the lower tanks 218 b, 218 c of the secondevaporator 218 have tube engaging holes (not shown), to which upper andlower ends of the tubes 222 of the heat exchange core 218 a areconnected in such a manner that the upper and lower ends of the tubes222 are communicated with interior spaces of the tanks 218 b, 218 c.

In this way, each of the upper and lower tanks 215 b, 215 c, 218 b, 218c has a role-of distributing the refrigerant flow to the tubes 222 ofthe corresponding heat exchange core 215 a, 218 a or a role ofcollecting the refrigerant flow from the tubes 222.

The distribution and collection of the refrigerant flow by the tanks 215b, 215 c, 218 b, 218 c will be more specifically described withreference to FIG. 20. In FIG. 20, an inlet 224, into which the lowpressure refrigerant on the downstream side of the ejector 214 issupplied, is arranged at the left end of the lower tank 215 c of thefirst evaporator 215, and an outlet 225 is arranged at the right end ofthe lower tank 215 c. A partition plate 226 is arranged generally in alongitudinal center of the interior space of the lower tank 215 c, whichis centered in the longitudinal direction of the interior space of thelower tank 215 c (in the stacking direction of the tubes 222 and thefins 223 of the heat exchange core 215 a). The partition plate 226divides the interior space of the lower tank 215 c into a left regionand a right region in FIG. 20.

Thus, the low pressure refrigerant, which is supplied from the inlet 224into the left region of the interior of the lower tank 215 c, flowsupward through a group of the left side tubes 222 of the heat exchangecore 215 a in a direction of arrow “a” and then flows from the left sideto the right side in the interior of the upper tank 215 b in a directionof arrow “b” in FIG. 20.

Then, the refrigerant, which is now located on the right region of theinterior of the upper tank 215 b, flows downward through a group ofright side tubes 222 of the heat exchange core 215 a in a direction ofarrow “c” and enters the right region of the interior of the lower tank215 c in FIG. 20. Then, the refrigerant is discharged in a direction ofarrow “d” in FIG. 20 from the outlet 225, which is located in the rightend of the lower tank 215 c, so that the refrigerant is directed towardan suctioning inlet side of the compressor 211.

In contrast, in the second evaporator 218, an inlet 227, into which thelow pressure refrigerant passed through the metering mechanism 217 ofthe branched passage 216 is supplied, is arranged at the right end ofthe upper tank 218 b. Furthermore, an outlet 228 is arranged at the leftend of the upper tank 218 b. A partition plate 229 is arranged generallyin a longitudinal center of the interior space of the upper tank 218 b,which is centered in the longitudinal direction of the interior space ofthe upper tank 218 b (in the stacking direction of the tubes 222 and thefins 223 of the heat exchange core 218 a). The partition plate 229divides the interior space of the upper tank 218 b into a left regionand a right region in FIG. 20.

Thus, the low pressure refrigerant, which is supplied from the inlet 227into the right region of the interior of the upper tank 218 b, flowsdownward through a group of right side tubes 222 of the heat exchangecore 218 a in a direction of arrow “e” and then flows from the rightside to the left side in the interior of the lower tank 218 c in adirection of arrow “f” in FIG. 20.

Then, the refrigerant, which is now located on the left region of theinterior of the lower tank 218 c, flows upward through a group of leftside tubes 222 of the heat exchange core 218 a in a direction of arrow“g” and enters the left region of the interior of the upper tank 218 bin FIG. 20. Then, the refrigerant is discharged in a direction of arrow“h” in FIG. 20 from the outlet 228, which is located in the left end ofthe upper tank 218 b, so that the refrigerant is directed toward thesuction inlet 214 b side of the ejector 214.

Next, the specific integral structure of the tubes 222, the fins 223 andthe tanks 215 b, 215 c, 218 b, 218 c of the two evaporators 215, 218will be described.

Separate arrangements of fins, which serve as the fins 223, may berespectively provided to the two heat exchange cores 215 a, 218 a, whichare arranged one after the other in the air flow A. Alternatively, acommon single arrangement of fins, which serve as the fins 223, may beprovided commonly to the two heat exchange cores 215 a, 218 a.

Similarly, separate arrangements of tubes, which serve as the tubes 222,may be respectively provided to the two heat exchange cores 215 a, 218a, which are arranged one after the other in the air flow A.Alternatively, a common single arrangement of tubes, which serve as thetubes 222, may be provided commonly to the two heat exchange cores 215a, 218 a.

However, the tubes 222 of the first evaporator 215 and the tubes 222 ofthe second evaporator 218 need to form completely independentrefrigerant passages, respectively. Thus, in the case where the integralsingle arrangement of tubes is used, the refrigerant passage of thefirst evaporator 215 and the refrigerant passage of the secondevaporator 218 need to be separated from each other by correspondingpartition walls provided in the tubes. In such a case, the refrigerantpassages, which are defined by the tubes of the first evaporator 215,need to be independently connected to the interiors of the upper andlower tanks 215 b, 215 c of the first evaporator 215. Also, therefrigerant passages, which are defined by the tubes of the secondevaporator 218, need to be independently connected to the interiors ofthe upper and lower tanks 218 b, 218 c of the second evaporator 218.

Also, the tanks 215 b, 215 c, 218 b, 218 c may be independently formed.Alternatively, the two upper tanks 215 b, 218 b may be constructedintegrally, and the two lower tanks 215 c, 218 c may be constructedintegrally. However, even in this case too, the interior spaces of theupper tanks 215 b, 218 b need to be formed independently of each other,and the interior spaces of the lower tanks 215 c, 218 c need to beformed independently of each other.

In addition, the left and right side plates 215 d, 215 e, 218 d, 218 emay be formed independently from each other. Alternatively, the two leftside plates 215 d, 218 d may be formed integrally as a single plate, andthe two right side plates 215 e, 218 e may be formed integrally as asingle plate.

As discussed above, when the tubes 222, the fins 223, the tanks 215 b,215 c, 218 b, 218 c and the side plates 215 d, 215 e, 218 d, 218 e ofthe first and second evaporators 215, 218 are constructed as theintegral structure, the number of components of the evaporators 215, 218can be reduced, and the manufacturing costs can be reduced.

A specific material of the tubes 222, the fins 223, the tanks 215 b, 215c, 218 b, 218 c and the side plates 215 d, 215 e, 218 d, 218 e ispreferably aluminum, which is the metal that exhibits the superiorthermal conductivity and the superior solderability. However, thematerial is not limited to the aluminum and can be any other suitablematerial. When each component of the first and second evaporators 215,218 is made from the aluminum material, the first and second evaporators215, 218 can be joined together by the soldering.

In the present embodiment, after the assembling of the first and secondevaporators 215, 218 by the soldering, the ejector 214 is installed tothe first and second evaporators 215, 218 to integrate the ejector 214with the first and second evaporators 215, 218.

As shown in FIG. 20, the ejector 214 is formed into an elongatedcylindrical body, in which the nozzle portion 214 a, the mixing portion214 c and the diffuser portion 214 d are arranged one after anotheralong a straight line. Thus, in the present embodiment, the ejector 214is assembled integrally to the lateral surfaces of the heat exchangecores 215 a, 218 a in such a manner that the longitudinal direction ofthe ejector 214 is made parallel to the lateral surfaces of the heatexchange cores 215 a, 218 a.

More specifically, the longitudinal direction of the ejector 214 isarranged parallel to the left side plates 215 d, 218 d of the heatexchange cores 215 a, 218 a, and the ejector 214 is installed to theleft side plates 215 d, 218 d. Here, the ejector 214 is secured to theside plates 215 d, 218 d by a securing means (not shown), such asscrews, metal spring clips or soldering.

With the above assembly structure of the ejector 214, the outlet of thediffuser 214 d of the ejector 214 can be positioned close to the inlet224 of the lower tank 215 c, and the suction inlet 214 b of the ejector214 can be positioned close to the outlet 228 of the upper tank 218 b.Thus, both the refrigerant passage connection between the ejector 214and the first evaporator 215 and the refrigerant passage connectionbetween the ejector 214 and the second evaporator 218 can be madesimple.

Furthermore, the longitudinal direction of the ejector 214, which ismade as the elongated cylindrical body, is arranged along the lateralsurfaces of the heat exchange cores 215 a, 218 a of the first and secondevaporators 215, 218, so that the ejector 214 will not protrudesignificantly outward from the first and second evaporators 215, 218. Asa result, the entire size of the first and second evaporators 215, 218and the ejector 214 can be made compact.

Next, operation of the thirteenth embodiment will be described. When thecompressor 211 is driven by the vehicle engine, the refrigerant iscompressed in the compressor 211. Then, the high temperature and highpressure refrigerant is discharged from the compressor 211 and issupplied to the radiator 213. In the radiator 213, the high temperaturerefrigerant is cooled by the external air and is thus condensed. In thebranch point Z, the high pressure liquid state refrigerant, which isdischarged from the radiator 213, is divided into a refrigerant flowdirected to the ejector 214 and a refrigerant flow directed to thebranched passage 216.

The refrigerant flow, which is supplied to the ejector 214, isdepressurized and is expanded at the nozzle portion 214 a. Thus, thepressure energy of the refrigerant is converted into the velocity energyat the nozzle portion 214 a, and thereby the refrigerant is dischargedat the high velocity from outlet of the nozzle portion 214 a. Due to thedecrease in the refrigerant pressure, the refrigerant (gas phaserefrigerant), which has passed through the second evaporator 218 in thebranched passage 216, is drawn through the suction inlet 214 b.

The refrigerant, which is discharged from the nozzle portion 214 a, andthe refrigerant, which is drawn through the suction inlet 214 b, aremixed in the mixing portion 214 c located on the downstream side of thenozzle portion 214 a and are then supplied to the diffuser portion 214d. In the diffuser portion 214 d, due to the increase in the passagecross sectional area, the velocity (expansion) energy is converted intothe pressure energy, so that the pressure of the refrigerant increases.

The refrigerant, which is discharged from the diffuser portion 214 d ofthe ejector 214, is supplied to the first evaporator 215. In the firstevaporator, while the refrigerant flows in the refrigerant flow pathindicated by the arrows a-d in FIG. 20, the low temperature low pressurerefrigerant absorbs the heat from the blown air, which is blown in thedirection of arrow A, and is thus evaporated. After the evaporation,this gas phase refrigerant is drawn into and is compressed in thecompressor 211 once again.

In contrast, the refrigerant flow, which is supplied to the branchedpassage 216, is depressurized in the metering mechanism 217 and thusbecomes the low pressure refrigerant. Then, the low pressure refrigerantis supplied to the second evaporator 218. In the second evaporator 218,while the refrigerant flows in the refrigerant flow path indicated bythe arrows e-h in FIG. 20, the refrigerant absorbs the heat from theblown air, which is blown in the direction of arrow A. After theevaporation, this gas phase refrigerant is drawn into the ejector 214through the suction inlet 214 b.

As discussed above, according to the present embodiment, the refrigeranton the downstream side of the diffuser portion 214 d of the ejector 214can be supplied to the first evaporator 215, and also the refrigerant inthe branched passage 216 can be supplied to the second evaporator 218through the metering mechanism 217. Thus, the first and secondevaporates 215, 218 can simultaneously perform its cooling operation.Therefore, the cooled air, which is cooled by both the first and secondevaporators 215, 218, can be discharged into the subject cooling space221 to cool the subject cooling space 221.

At this time, the refrigerant evaporation pressure of the firstevaporator 215 is the pressure of the refrigerant after the increasingof the pressure in the diffuser 214 d, and the outlet of the secondevaporator 218 is connected to the suction inlet 214 b of the ejector214. Thus, the lowest pressure right after the depressurization in thenozzle portion 214 a can be applied to the second evaporator 218.

In this way, the refrigerant evaporation pressure (the refrigerantevaporation temperature) of the second evaporator 218 can be made lowerthan that of the first evaporator 215. Furthermore, the first evaporator215, which has the higher refrigerant evaporation temperature, isarranged on the upstream side in the air flow direction A, and thesecond evaporator 218, which has the lower refrigerant evaporationtemperature, is arranged on the downstream side in the air flowdirection A. Thus, the required temperature difference between therefrigerant evaporation temperature and the blown air temperature at thefirst evaporator 215 and the required temperature difference between therefrigerant evaporation temperature and the blown air temperature at thesecond evaporator 218 can be both satisfied.

As a result, the cooling performance of the first evaporator 215 and thecooling performance of the second evaporator 218 can be effectivelyachieved. Therefore, the cooling performance for cooling the commonsubject cooling space 221 can be effectively improved by the combinationof the first and second evaporators 215, 218. Furthermore, the intakepressure of the compressor 221 is increased by the pressure increasingoperation of the diffuser portion 214 d, so that the required driveforce for driving the compressor 211 can be reduced.

Also, in the cycle 210 of the present embodiment, the branched passage216, which is branched at the branch point Z, is connected to thesuction inlet 214 b of the ejector 214, and the metering mechanism 217and the second evaporator 218 are arranged in the branched passage 216.Thus, the low pressure two-phase refrigerant of a gas and liquid mixturecan be supplied to the second evaporator 218 through the branchedpassage 216. Therefore, it is not required to provide the gas-liquidseparator of, for example, Japanese Patent No. 33222263 (correspondingto U.S. Pat. Nos. 6,477,857 and 6,574,987).

In the case where the super-critical cycle, in which the abovegas-liquid separator is provided, and the refrigerant, such as CO₂,which has the high cycle pressure that exceeds the critical pressure, isused, when the operation of the cycle is stopped under the high externaltemperature, the low pressure side of the cycle also becomes thecritical state in addition to the high pressure side.

Thus, the gas phase refrigerant and the liquid phase refrigerant cannotbe separated by the gas-liquid separator at the time of restarting thecycle operation. Therefore, the high temperature refrigerant of thesuper-critical state, which is present in the gas-liquid separator, issupplied to the second evaporator 218, so that the cooling performanceof the second evaporator 218 is significantly reduced. In contrast,according to the present embodiment, the high pressure refrigerant isbranched off on the upstream side of the ejector 214, and this branchedrefrigerant is depressurized through the metering mechanism 217 tosupply the low pressure refrigerant to the inlet side of the secondevaporator 218. As a result, the cooling performance of the secondevaporator 218 can be quickly enabled even at the time of restarting thecycle operation.

Furthermore, in a sub-critical cycle (cycle having its high pressurewithout exceeding the critical pressure), which uses the ordinaryfluorocarbon refrigerant, the pressure difference between the highpressure and the low pressure of the cycle becomes small in the smallcycle thermal load condition, so that the input to the ejector 214 isreduced. In such a case, in the cycle recited in Japanese Patent No.33222263, the refrigerant flow, which passes through the secondevaporator 218, depends only on the refrigerant drawing performance ofthe ejector 214. Thus, when the decrease in the input of the ejector 214occurs, the refrigerant drawing performance of the ejector 214 isreduced, and the refrigerant flow rate of the second evaporator 218 isreduced. Therefore, it is difficult to achieve the required coolingperformance of the second evaporator 218.

In contrast, according to the present embodiment, the high pressurerefrigerant is branched on the upstream side of the ejector 214, andthis branched refrigerant is drawn into the suction inlet 214 b of theejector 214 through the branched passage 216. Thus, the branched passage216 is connected in parallel with the ejector 214.

Therefore, besides the refrigerant drawing performance of the ejector214, the refrigerant drawing performance and the refrigerant dischargingperformance of the compressor 211 can be utilized to supply therefrigerant in the branched passage 216. In this way, even when theinput of the ejector 214 is reduced to cause the reduction of therefrigerant drawing performance of the ejector 214, the decrease in therefrigerant flow rate on the second evaporator 218 side can bealleviated in comparison to the cycle recited in Japanese Patent No.33222263. Therefore, even in the low thermal load condition, therequired cooling performance of the second evaporator can be more easilyachieved.

Furthermore, the refrigerant flow rate on the second evaporator 218 sidecan be independently adjusted by the metering mechanism 217 withoutrelying on the function of the ejector 214. The flow rate of therefrigerant, which is supplied to the first evaporator 215, can beadjusted through the control of the refrigerant discharging performanceof the compressor 211 and the metering characteristics of the ejector214. Thus, the flow rate of the refrigerant to the first evaporator 215and the flow rate of the refrigerant to the second evaporator 218 can beeasily adjusted depending on the thermal load of the first evaporator215 and the thermal load of the second evaporator 218, respectively.

FOURTEENTH EMBODIMENT

In the thirteenth embodiment, the ejector 214 is assembled integrally tothe lateral surfaces of the heat exchange cores 215 a, 218 a in such amanner that the longitudinal direction of the ejector 214 is madeparallel to the lateral surfaces of the heat exchange cores 215 a, 218a. In the fourteenth embodiment, as shown in FIG. 21, the ejector 214 isassembled integrally to the tanks 215 b, 215 c, 218 b, 218 c in such amanner that the longitudinal direction of the ejector 214 is madeparallel to the tanks 215 b, 215 c, 218 b, 218 c.

More specifically, in the exemplary case of FIG. 21, the ejector 214 isassembled integrally to the top surfaces of the upper tanks 215 b, 218 bin such a manner that the longitudinal direction of the ejector 214 ismade parallel to the top surfaces of the upper tanks 215 b, 218 b. Thesecuring means for securing the ejector 214 to the top surfaces of theupper tanks 215 b, 218 b may be the same as that of the thirteenthembodiment.

Next, the refrigerant passage structures of the first and secondevaporators 215, 218 will be described. In the first evaporator 215, thepartition plate 226 is provided in the upper tank 215 b to divide theinterior space of the upper tank 215 b into the left region and theright region in FIG. 21. The inlet 224 is arranged in the right regionof the top surface of the upper tank 215 b, and the downstream sidepassage of the diffuser portion 214 d of the ejector 214 is connected tothe inlet 224. Furthermore, the outlet 225 is arranged in the lateralsurface of the left region of the upper tank 215 b.

The refrigerant, which is supplied from the inlet 224 to the rightregion of the upper tank 215 b, passes through the right region of theheat exchange core 215 a, the lower tank 215 c, the left region of theheat exchange core 215 a and the left region of the upper tank 215 b inthis order and is discharged from the outlet 225 toward the inlet of thecompressor 221, as indicated by arrows i, k, m and n in FIG. 21.

In the second evaporator 215, similar to the thirteenth embodiment, thepartition plate 229 is provided in the upper tank 218 b to divide theinterior space of the upper tank 218 b into the left region and theright region in FIG. 21. The inlet 227 is arranged in the rear surfaceof the right region of the upper tank 218 b, and a connection pipe 216a, which is arranged on the downstream side of the metering mechanism217 of the branched passage 216, is connected to the inlet 227.

The refrigerant, which is supplied from the inlet 227 to the rightregion of the upper tank 218 b, passes through the right region of theheat exchange core 218 a, the lower tank 218 c, the left region of theheat exchange core 218 a and the left region of the upper tank 218 b inthis order and is supplied to the suction inlet 214 b of the ejector214, as indicated by arrows p, q, r and s in FIG. 21.

In the fourteenth embodiment, the location of the ejector 214 and therefrigerant passage structures of the first and second evaporators 215,218 are different from those of the thirteenth embodiment. However, thearrangement of the first and second evaporators 215, 218 with respect tothe air flow direction A and the passage structure of the cycle 210 arethe same as those of the thirteenth embodiment. Thus, advantages similarto those of the thirteenth embodiment are also achieved in thefourteenth embodiment.

FIFTEENTH EMBODIMENT

In the thirteenth and fourteenth embodiments, the branched passage 216,which is branched on the upstream side of the ejector 214 and isconnected to the suction inlet 214 b of the ejector 214, is provided,and the second evaporator 218 is provided in the branched passage 216.However, in the fifteenth embodiment, the branched passage 216 is notprovided.

That is, in the fifteenth embodiment, as shown in FIG. 22, a gas-liquidseparator 230 is provided on the downstream side of the first evaporator215 to separates the refrigerant of the gas and liquid mixture into thegas phase refrigerant and the liquid phase refrigerant. A gas phaserefrigerant outlet of the gas-liquid separator 230 is connected to theinlet of the compressor 211, and a liquid phase refrigerant outlet ofthe gas-liquid separator 230 is connected to the suction inlet 214 b ofthe ejector 214 through a branched refrigerant passage (or simplyreferred to as a branched passage) 231. The metering mechanism 217 andthe second evaporator 218 are provided in the branched passage 231.

The arrangement of the first and second evaporators 215, 218 withrespect to the air flow direction A is the same as that of thethirteenth and fourteenth embodiments. Thus, the first evaporator 215,which has the higher refrigerant evaporation temperature, is arranged onthe upstream side in the air flow direction, and the second evaporator218, which has the lower refrigerant evaporation temperature, isarranged on the downstream side in the air flow direction A. The firstand second evaporators 215, 218 are integrated by the structure shown inFIGS. 20 or 21.

Even in the fifteenth embodiment, the cooling performance for coolingthe subject cooling space 221 is advantageously improved by thecombination of the first and second evaporators 215, 218, which have thedifferent refrigerant evaporation temperatures.

SIXTEENTH EMBODIMENT

In the sixteenth embodiment, the cycle structure of the thirteenth orfourteenth embodiment is modified. Specifically, as shown in FIG. 23,the cycle structure of the sixteenth embodiment includes first andsecond low pressure passages 232, 233, which are branched from thedownstream side of the ejector 214 and are connected to the input sideof the compressor 211. Furthermore, the first and second low pressurepassages 232, 233 are arranged in parallel. The cycle structure furtherincludes first and second branched refrigerant passages (or simplyreferred to as first and second branched passages) 216 c, 216 d, whichare branched at the upstream side of the ejector 214 and are connectedto the suction inlet 214 b of the ejector 214.

The two first evaporators 215 f, 215 g are provided in the first andsecond low pressure passages 232, 233, respectively, on the downstreamside of the ejector 14. Two metering mechanisms 217 a, 217 b arearranged in the first and second branched passages 216 c, 216 d,respectively, and the two second evaporators 218 f, 218 g are providedon the downstream side of the metering mechanisms 217 a, 217 b,respectively.

In the sixteenth embodiment, the first evaporator 215 f and the secondevaporator 218 f are constructed integrally (assembled integrally orformed integrally) and are received in a single common case 219 a. Acommon electric blower (not shown but corresponding to the blower 220 ofFIG. 19) blows the air (air to be cooled) to an air passage in the case219 a, as indicated by an arrow A1 in FIG. 23, so that the blown air iscooled by the two evaporators 215 f, 218 f.

Similarly, the first evaporator 215 g and the second evaporator 218 gare constructed integrally, assembled integrally or are formedintegrally and are received in a single common case 219 b. A commonelectric blower (not shown but corresponding to the blower 220 of FIG.19) blows the air (air to be cooled) to an air passage in the case 219b, as indicated by an arrow A2 in FIG. 23, so that the blown air iscooled by the two evaporators 215 g, 218 g.

The integration of the first evaporator 215 f and the second evaporator218 f and the integration of the first evaporator 215 g and the secondevaporator 218 g can be implemented by the structure shown in FIG. 20 orFIG. 21. The ejector 214 may be integrally assembled to any desired oneof the integrated structure of the first and second evaporators 215 f,218 f and the integrated structure of the first and second evaporators215 g, 218 g.

The cool air, which is cooled by the two evaporators 215 f, 218 f in thecase 219 a, is supplied into the common subject cooling space (notshown), so that the common subject cooling space is cooled by the twoevaporators 215 f, 218 f.

Similarly, the cool air, which is cooled by the two evaporators 215 g,218 g in the case 219 b, is supplied into the common subject coolingspace (not shown), so that the common subject cooling space is cooled bythe two evaporators 215 g, 218 g.

The subject cooling space of the case 219 a and the subject coolingspace of the case 219 b are formed independently from each other. Thesubject cooling space of the case 219 a may be, for example, thepassenger compartment of the vehicle, and the subject cooling space ofthe case 219 b may be, for example, the freezer/refrigerator space ofthe freezer/refrigerator vehicle.

In the sixteenth embodiment, each first evaporator 215 f, 215 g, whichhas the higher refrigerant evaporation temperature, is arranged on theupstream side in the corresponding air flow direction A1, A2, and eachsecond evaporator 218 f, 218 g, which has the lower refrigerantevaporation temperature, is arranged on the downstream side in thecorresponding air flow direction A1, A2.

The thirteenth to sixteenth embodiments can be modified in various ways,as discussed below.

(1) In the cycle 210 of the thirteenth and sixteenth embodiments shownin FIGS. 19 and 23, there is not provided the gas-liquid separator,which separates the refrigerant of gas and liquid mixture into the gasphase refrigerant and the liquid phase refrigerant and accumulates theexcessive refrigerant as the liquid refrigerant. However, for example, agas-liquid separator (receiver), which separates the refrigerant of gasand liquid mixture into gas phase refrigerant and liquid phaserefrigerant and accumulates the liquid phase refrigerant, may beprovided at the outlet side of the radiator 213, so that the liquidphase refrigerant is supplied from the gas-liquid separator to theejector 214. Furthermore, a gas-liquid separator (accumulator), whichseparates the refrigerant of gas-liquid mixture into gas phaserefrigerant and liquid phase refrigerant and accumulates excessiverefrigerant as the liquid phase refrigerant, may be provided at theinlet side of the compressor 211, so that the gas phase refrigerant issupplied from the gas-liquid separator to the inlet of the compressor211.

(2) In each of the above embodiments, the vehicular refrigeration cycleis described. However, the present invention is not limited to thevehicular refrigeration cycle and can be equally applicable to astationary refrigeration cycle, which is settled stationary.

(3) In each of the above embodiments, the type of refrigerant is notspecified. However, it should be noted that the refrigerant of the aboveembodiments may be a fluorocarbon refrigerant (includingchlorofluorocarbon refrigerant), an alternative for thechlorofluorocarbon refrigerant, such as hydrocarbon (HC) refrigerant, orcarbon dioxide (CO₂), which can be used in any one of the vaporcompression type super critical cycle and the vapor compression typesub-critical cycle.

Here, it should be noted that the chlorofluorocarbon is a generic nameof an organic compound composed of carbon, fluorine, chlorine andhydrogen and is widely used as the refrigerant. Furthermore, thefluorocarbon refrigerants include hydrochlorofluorocarbon (HCFC)refrigerant, hydrofluorocarbon (HFC) refrigerant, which do not destroythe ozone layer and thus are called as substitutes for thechlorofluorocarbon.

The hydrocarbon (HC) refrigerant is a refrigerant that includes hydrogenand carbon and is found in nature. The HC refrigerants include R600a(isobutene), R290 (propane) and the like.

(4) In each of the above embodiments, a flow rate variable type ejector,in which a cross sectional area of the refrigerant passage of the nozzleportion 214 a, i.e., a refrigerant flow rate in the nozzle portion 214 ais adjusted, may be used as the ejector 214.

(5) In contrast to each of the above embodiments, the first evaporator215, 215 f, 215 g, which has the higher refrigerant evaporationtemperature, may be arranged on the downstream side in the air flowdirection A, A1, A2, and the second evaporator 218, 218 f, 218 g, whichhas the lower refrigerant evaporation temperature, may be arranged onthe upstream side in the air flow direction A1, A2.

(6) With reference to FIG. 24, the first evaporator 215 and the secondevaporator 218 may be connected to each other by a refrigerant pipeline340 through the ejector 214. More specifically, the outlet of the secondevaporator 218 may be connected to the suction inlet 214 b of theejector 214 by a portion of the pipeline 340, and the outlet of thediffuser portion 214 d of the ejector 214 may be connected to the inletof the first evaporator 215 by another portion of the pipeline 340. Inthis instance, as shown in FIG. 24, the first and second evaporators215, 218 may be constructed integrally in such a manner that apredetermined space is provided between the first evaporator 215 and thesecond evaporator 218, and the refrigerant pipeline 340 integrallyconnects between the first and second evaporators 215, 218 whilelimiting disassembly between the first and second evaporators 215, 218.

Additional advantages and modifications will readily occur to thoseskilled in the art. The invention in its broader terms is therefore notlimited to the specific details, representative apparatus, andillustrative examples shown and described. Furthermore, it should benoted that the feature(s) of one of the above-described embodiments ormodification(s) can be combined with the feature(s) of any other one ofthe above-described embodiments or modification(s).

1. A vapor compression cycle comprising: a compressor that draws andcompresses refrigerant; a radiator that radiates heat from thecompressed high pressure refrigerant discharged from the compressor; anejector that includes: a nozzle portion, which depressurizes and expandsthe refrigerant on a downstream side of the radiator; a refrigerantsuction inlet, from which refrigerant is drawn by action of a flow ofthe high velocity refrigerant discharged from the nozzle portion; amixing portion, through which the high velocity refrigerant dischargedfrom the nozzle portion and the drawn refrigerant supplied from thesuction inlet are mixed; and a pressurizing portion that converts avelocity energy of a flow of mixed refrigerant, which is mixed throughthe mixing portion, into a pressure energy; a first evaporator that isconnected to a downstream side of the ejector; and a second evaporatorthat is connected to the suction inlet of the ejector, wherein the firstevaporator and the second evaporator are constructed integrally to coolan air flow that is directed to a common subject cooling space.
 2. Thevapor compression cycle according to claim 1, wherein the firstevaporator and the second evaporator are connected to each other to forma continuous structure.
 3. The vapor compression cycle according toclaim 2, wherein the first evaporator and the second evaporator arejoined together by soldering.
 4. The vapor compression cycle accordingto claim 2, wherein the first evaporator and the second evaporator areconnected to each other by a refrigerant pipeline through the ejector.5. The vapor compression cycle according to claim 1, wherein the firstevaporator and the second evaporator are arranged in series in the airflow.
 6. The vapor compression cycle according to claim 5, wherein: arefrigerant evaporation temperature of the second evaporator is lowerthan a refrigerant evaporation temperature of the first evaporator; thefirst evaporator is arranged on an upstream side of the air flow; andthe second evaporator is arranged on a downstream side of the air flow.7. The vapor compression cycle according to claim 1, wherein each of thefirst and second evaporators includes: a heat exchange core that has astack structure of a plurality of tubes and a plurality of fins, whereineach of the tubes forms a refrigerant passage, and the fins areconnected to outer surfaces of the tubes to increase a heat transfersurface area for exchanging heat with the air flow; and at least onetank, to which ends of the plurality of tubes are connected todistribute and collect the refrigerant relative to the plurality oftubes.
 8. The vapor compression cycle according to claim 7, wherein theplurality of tubes, the plurality of fins and the at least one tank ofthe first evaporator and the plurality of tubes, the plurality of finsand the at least one tank of the second evaporator are integrallyassembled together by soldering.
 9. The vapor compression cycleaccording to claim 7, wherein: the ejector is formed as an elongatedbody, in which the nozzle portion, the mixing portion and thepressurizing portion of the ejector are arranged along a straight line;a longitudinal direction of the ejector is parallel to a lateral surfaceof the heat exchange core of at least one of the first and secondevaporators; and the ejector is assembled integrally to the lateralsurface of the heat exchange core of the at least one of the first andsecond evaporators.
 10. The vapor compression cycle according to claim7, wherein: the ejector is formed as an elongated body, in which thenozzle portion, the mixing portion and the pressurizing portion of theejector are arranged along a straight line; and a longitudinal directionof the ejector is parallel to a longitudinal direction of the at leastone tank of at least one of the first and second evaporators; and theejector is assembled integrally to at least one of: one of the at leastone tank of the first evaporator; and one of the at least one tank ofthe second evaporator.
 11. The vapor compression cycle according toclaim 1, further comprising: a branched refrigerant passage that isbranched at a branch point on an upstream side of the ejector andextends to the suction inlet of the ejector; and a metering mechanismthat is inserted in the branched refrigerant passage, wherein the secondevaporator is located on a downstream side of the metering mechanism.12. The vapor compression cycle according to claim 1, further comprisinga gas-liquid separator that is arranged on a downstream side of thefirst evaporator to separate refrigerant into gas phase refrigerant andliquid phase refrigerant, wherein: a gas phase refrigerant outlet of thegas-liquid separator is connected to an inlet of the compressor; aliquid phase refrigerant outlet of the gas-liquid separator is connectedto the suction inlet of the ejector through a branched refrigerantpassage; the vapor compression cycle further comprises a meteringmechanism that is inserted in the branched refrigerant passage; and thesecond evaporator is arranged on a downstream side of the meteringmechanism.